Opinion
SHEA, J.In this proceeding for termination of the parental rights of the respondents with respect to their son, David, both the father (AC 17313) and the mother *578(AC 17564) have appealed from the judgment of the trial court granting the petition of the commissioner of children and families (commissioner) seeking such termination. The trial court relied on two of the grounds for terminating parental rights set forth in General Statutes (Rev. to 1995) § 17a-112 (b):1 “(2) the parent of a child who has been found by the superior court to have been neglected or uncared for in a prior proceeding has failed to achieve such degree of personal rehabilitation as would encourage the belief that within a reasonable time, considering the age and needs of the child, *579such parent could assume a responsible position in the life of the child; [and] (3) the child has been denied, by reason of an act or acts of parental commission or omission, the care, guidance or control necessary for his physical, educational, moral or emotional well-being. Nonaccidental or inadequately explained serious physical injury to a child shall constitute prima facie evidence of acts of parental commission or omission sufficient for the termination of parental rights . . . .”
In seeking to reverse the judgment, the respondents contend that (1) the doctrine of res judicata bars reliance on General Statutes (Rev. to 1995) § 17a-112 (b) (2) , which requires a prior adjudication that a child has been neglected or uncared for, (2) the petitioner was estopped from claiming that the respondents had not achieved a sufficient degree of rehabilitation to resume their parental roles because certain employees of the department had assured them that their progress toward reunification with their child had been good and (3) the trial court should have stricken the testimony of a psychologist who had been appointed by the court to evaluate the rehabilitation progress of the parents because he had also been contacted by counsel for the department to testify as its expert witness concerning the rehabilitation of the parents. We conclude that there is no merit in the claim of res judicata and that the claimed misrepresentations made to the parents had no impact on the judgment, but that the motion to strike the testimony of the psychologist should have been granted because of his agreement to act as an expeit witness for the department of children and families (department) after he had been appointed by the trial court to evaluate the parents and because of his ex parte contacts with counsel for the department.
*580The facts found by the trial court as recited in the memorandum of decision are unchallenged. The child was bom to the respondents on July 12, 1993. He was bom three months premature, weighing only three pounds, nine ounces, and remained in the hospital for eighteen days. He was discharged on August 1, 1993, and lived with his parents until September 5, 1993. On that date, he was brought to a hospital after having sustained multiple life threatening injuries: four fractures of the left ribs; a fracture showing interval healing of the right femur; a spiral fracture of the left femur; a distal fracture of the left femur, which appeared to have healed; two recent fractures of the right tibia and fibula; a collapsed lung and multiple bruises and petechiae on the face, neck and chest, probably caused by the child’s screaming in pain according to the testimony of a physician. The parents had exclusive control and custody of the child immediately preceding his injuries. They offered no reasonable explanation for the injuries sustained by their child.
On September 8,1993, the child was discharged from the hospital and placed in the care of the department, which obtained an order of temporary custody on the same date. After a study by the department foster care unit, he was placed with a couple known to the respondents. The child has resided with the couple since December 24, 1993, but the respondents have visited him, as permitted by the department, since that time, either at their home or at the home of the foster parents. On January 11,1994, the respondents pleaded nolo con-tendere to the neglect petition that the commissioner had filed. The court, Barnett, J., adjudicated the child to be a neglected child pursuant to General Statutes (Rev. to 1993) § 46b-129 (d)2 and committed him to the commissioner in accordance with that statute.
*581As mandated by General Statutes (Rev. to 1995) § 17a-112 (d),3 the trial court also made findings regarding the services provided by the department to facilitate reunion of the child with the parents and other related matters specified in that statute. No issue has been raised about the sufficiency of the evidence to support those findings or compliance of the findings with the *582statute as a prerequisite for the judgment of termination.
I
The respondents argue that res judicata requires reversal of the judgment of the trial court terminating their parental rights because of the failure of the commissioner to seek such termination in the neglect proceeding in which the commissioner sought custody of the child after learning of the injuries he had sustained while living with his parents. “[C]laim preclusion [or res judicata] prevents a litigant from reasserting a claim that has already been decided on the merits. . . . Under claim preclusion analysis, a claim—that is, a cause of action—includes all rights of the plaintiff to remedies against the defendant with respect to all or any part of the transaction, or series of connected transactions, out of which the action arose. . . . Moreover, claim preclusion prevents the pursuit of any claims relating to the cause of action which were actually made or might have been made.” (Citations omitted; internal quotation marks omitted.) Scalzo v. Danbury, 224 Conn. 124, 127-28, 617 A.2d 440 (1992). “The doctrines of preclusion, however, should be flexible and must give way when their mechanical application would frustrate other social policies based on values equally or more important than the convenience afforded by finality in legal controversies.” In re Juvenile Appeal (83-DE), 190 Conn. 310, 318, 460 A.2d 1277 (1983).
The legislative goal of reuniting a neglected child with its parents, when feasible, would be seriously undermined by allowing the judgment transferring custody to the commissioner in a neglect proceeding to bar a subsequent petition for termination of parental rights, even though the neglect adjudication constitutes part of the ground for termination set forth in § 17a-112 (b) (2). That subsection refers explicitly to “the *583parent of a child who has been found by the superior court to have been neglected or uncared for in a prior proceeding . . . .” (Emphasis added.) General Statutes (Rev. to 1995) § 17a-112 (b) (2). The statute further requires that the parent of such a child be found to have “failed to achieve such degree of personal rehabilitation as would encourage the belief that within a reasonable time, considering the age and needs of the child, such parent could assume a responsible position in the life of the child . . . .” General Statutes (Rev. to 1995) § 17a-112 (b) (2). Furthermore, “[e]xcept in the case where termination is based on consent, in determining whether to terminate parental rights under this section, the court shall consider and shall make written findings regarding: (1) The timeliness, nature and extent of services offered or provided to the parent and the child by an agency to facilitate the reunion of the child with the parent . . . [and] (6) the efforts the parent has made to adjust his circumstances, conduct, or conditions to make it in the best interest of the child to return him to his home in the foreseeable future . . . .” General Statutes (Rev. to 1995) § 17a-112 (d).
Although General Statutes (Rev. to 1995) § 17a-112 (e)4 does provide that a neglect petition “may be accompanied by or, upon motion by the petitioner, consolidated with a petition for termination of parental rights,” that procedure is not mandatory but optional on the *584part of the commissioner. When § 17a-112 (b) (2) is the ground for termination, the requirement that the adjudication of neglect occur “in a prior proceeding” indicates that the termination proceeding may not be combined with the neglect proceeding and that separate judgments on each petition are necessary. The mandatory findings required by § 17a-112 (d) concerning the services to be provided to the parent of a child found to have been neglected and the efforts of such a parent to adjust his conduct so that reunification with the child might be achieved could not be made unless there was sufficient time between the judgment on the neglect petition and the hearing on the termination petition to make the studies needed to present the evidence for the prescribed findings. We conclude that, because our statutes require those findings, there must be a sufficient hiatus for that purpose between the adjudications of neglect and termination petitions and, accordingly, the termination judgment in this case is not barred by the prior judgment on the neglect petition. Each petition pertains to a separate transaction and, therefore, the doctrine of res judicata is not applicable. See Duhaime v. American Reserve Life Ins. Co., 200 Conn. 360, 364-65, 511 A.2d 333 (1986).
II
The respondents next claim that the commissioner should be estopped from maintaining that they had not made sufficient progress in achieving rehabilitation toward the goal of reunification with their child because of statements made by employees of the department to the respondents that their progress toward that goal was good. We conclude that there was a lack of candor on the part of the department, but that the misrepresentations made to the respondents concerning their rehabilitation had no adverse impact on the respondents or on the judgment.
*585The initial case review in October, 1993, after the child had been released from the hospital and placed in a foster home, indicated that the placement goal of the department was reunification within twelve to eighteen months. In successive six month reviews, the goal of reunification remained unchanged and the progress of the respondents toward that goal was reported as good. The caseworker assigned to the respondents testified, however, that in March, 1995, more than two years after the judgment on the neglect petition, the commissioner decided to seek termination of the respondents’ parental rights. She believed that the attorney for the respondents was informed of that decision during a court proceeding that took place about that time. A detailed case study report recommending termination and signed by four employees of the department was completed on November 1, 1995. The petition for termination of the respondents’ parental rights was filed on November 3, 1995. Even after the petition had been filed, the six month case reviews nevertheless continued to indicate that the goal was rehabilitation and that the respondents’ progress was good. In response to an inquiry on cross-examination as to why the department continued to indicate reunification as the goal when the commissioner had already decided to file a termination petition, the social worker assigned to the case testified that it was the department’s policy not to change the reunification goal even after a decision to file a termination petition had been reached, as long as therapy was still being offered by the department. She admitted that she had told the respondents that they were doing what they were supposed to do with respect to rehabilitation therapy.
The respondents claim that the doctrine of promissory estoppel is applicable because of the assurances they received from employees of the department concerning their progress in rehabilitation therapy toward *586ultimate reunification with their son. “A promise which the promisor should reasonably expect to induce action or forbearance on the part of the promisee or a third person and which does induce such action or forbearance is binding if injustice can be avoided only by enforcement of the promise.” 1 Restatement (Second), Contracts § 90 (1981). “A fundamental element of promissory estoppel, therefore, is the existence of a clear and definite promise which a promisor could reasonably have expected to induce reliance.” D’Ulisse-Cupo v. Board of Directors of Notre Dame High School, 202 Conn. 206, 213, 520 A.2d 217 (1987). The statements of the employees of the department to the respondents concerning their rehabilitation progress can hardly constitute promises because no performance by the promi-sor is implicated. The trial court was not compelled to conclude that those few words of encouragement would qualify as a clear and definite promise on which the respondents would reasonably be expected to rely with respect to the return of their child.
Although the respondents have not raised a claim of equitable estoppel, it is appropriate to address it in the present case because of the close relationship between promissory and equitable estoppel. The absence of a clear and definite promise would not preclude application of the doctrine of equitable estoppel, but its two essential elements must be proved: “the party against whom estoppel is claimed must do or say something calculated or intended to induce another to believe that certain facts exist and to act on that belief; and the other party must change its position in reliance on those facts, thereby incurring some injury.” Zoning Commission v. Lescynski, 188 Conn. 724, 731, 453 A.2d 1144 (1982). The statements made to the respondents that their progress in therapy was good, encouraging them to continue attending the therapy sessions, might arguably satisfy the first element, but there is no basis in the *587evidence for concluding that they suffered any detriment therefrom, as the second element requires. The trial court found that they had attained a degree of personal rehabilitation that was “personally beneficial and encouraging to them individually and collectively.” The trial court also acknowledged “impressive rehabilitation by the parents that has tremendously improved their personal and marital prospects.” The memorandum of decision states that “the couple has made excellent progress in all areas but one, acknowledgment and acceptance of personal responsibility for causing multiple, serious life threatening injuries to their own infant child.” There is no evidence that the therapy that the respondents received was harmful in any manner.
It must be remembered that the petitioner in this case is the commissioner of an agency of the state of Connecticut. “[Ejstoppel against a public agency is limited and may be invoked: (1) only with great caution; (2) only when the action in question has been induced by an agent having authority in such matters; and (3) only when special circumstances make it highly inequitable or oppressive not to estop the agency.” Kimberly-Clark Corp. v. Dubno, 204 Conn. 137, 148, 527 A.2d 679 (1987). The respondents could not have reasonably assumed that the employee of the department who told them that their progress in rehabilitation was good had the authority to make the ultimate determination of whether they would likely achieve a degree of rehabilitation sufficient to warrant return of their child. The statements claimed as misrepresentations may well have encouraged the respondents to continue their course of therapy, from which they have benefited significantly, as the trial court found. We conclude that the trial court properly rejected the respondents’ claim of estoppel.
Ill
Before the trial of the present case, the trial court appointed a clinical psychologist to evaluate the suit*588ability of the respondents as parents in the event that their child was returned to them. The appointment was made pursuant to an agreement of the parties. The psychologist testified that someone on whom the parties had agreed informed him of his appointment. See Practice Book § 25-33, which became effective October 1, 1997, after the trial of this case.
On cross-examination, the psychologist testified that he was contacted by an assistant attorney general, who asked him to meet with her to review the case, and he did so. She asked him to do a developmental assessment and a home study. A social worker called him and requested that he do the follow-up developmentals and collateral contacts. The psychologist testified that each time he was contacted he was told whether he was working for the court or for some other party. He admitted that, with respect to at least one of the evaluations he had made, he knew he was not acting as a court-ordered evaluator. He also testified that he was told not to talk to other counsel without direction from the assistant attorney general and that he may have refused to talk with counsel for the respondents without such consent.
Counsel for the respondent father5 moved to strike the psychologist’s testimony on the ground that he could not simultaneously purport to be a neutral court-appointed witness and also serve as an expert witness on behalf of the department. The trial court denied the motion, ruling that the psychologist’s agreement to *589serve as an expert witness for the department after his appointment by the trial court might affect the weight of his testimony but not its admissibility.
“A basic purpose of appointing an expert is to provide the trier of fact with a neutral viewpoint when the parties’ experts are in conflict.” 29 C. Wright & V. Gold, Federal Practice and Procedure (1997) § 6305, p. 482. “An expert witness appointed by the trial court to obtain disinterested and unbiased testimony, either under statute or pursuant to its inherent power, is an officer of the court and does not appear as the witness of either party.” 31A Am. Jur. 2d, Expert and Opinion Evidence § 16 (1989); United States v. Theriault, 440 F.2d 713, 715 (5th Cir. 1971). “Fairness requires that the examining psychiatrist pursuant to a § 4244 motion [to determine competency of a defendant to stand trial] be an officer of the Court and responsible neither to the defense nor the prosecution.” United States v. Pogany, 465 F.2d 72, 78 (3d Cir. 1972). Even the court should refrain from ex parte contact with an expert it has appointed to serve as a neutral witness.6 United States v. Green, 544 F.2d 138, 146 n.16 (3d Cir. 1976), cert. denied sub nom. Tefsa v. United States, 430 U.S. 910, 97 S. Ct. 1185, 51 L. Ed. 2d 588 (1977).
If obtaining impartial expert testimony was the purpose for appointing the psychologist who testified for the department in this case as the court’s expert witness, that objective plainly was not achieved. Unauthorized ex parte communications with a court-appointed *590witness, such as those that took place with an assistant attorney general acting on behalf of the department, are improper. The refusal of the supposedly neutral expert to talk to counsel for the respondent, in contrast to his willingness to confer with the attorney for the department, indicates that he was wholly unaware of his obligations as a court-appointed expert. His agreement to testify on behalf of the department after his appointment as the court’s expert was plainly in conflict with the neutral role he necessarily assumed when he accepted that appointment. We conclude that the court should have granted the motion to strike the testimony of its appointed expert because of the conflict created by his agreement to testify on behalf of the department and also because of the ex parte contacts with counsel for the department.
The denial of the motion cannot be regarded as a harmless error, as the dissenting opinion contends. The memorandum of decision indicates that the trial court relied substantially on the testimony of its appointed expert in deciding that the respondents’ parental rights should be terminated. The experts who testified on behalf of the respondents, a licensed marriage and family therapist and a clinical psychologist, opined that more time should be allowed for reunification, which could be accomplished by increasing visitation gradually.
The judgment is reversed and the case is remanded for a new trial.
In this opinion SULLIVAN, J., concurred.
General Statutes (Rev. to 1995) § 17a-112 (b), as amended by Public Acts 1995, No. 95-238, provides: “The superior court upon hearing and notice, as provided in sections 45a-716 and 45a-717, may grant such petition if it finds that the department of children and families has made reasonable efforts to reunify the child with the parent and, upon clear and convincing evidence, that the termination is in the best interest of the child and that, with respect to any consenting parent, such parent has voluntarily and knowingly consented to termination of his parental rights with respect to such child or that, with respect to any nonconsenting parent, over an extended period of time, which, except as provided in subsection (c) of this section, shall not be less than one year: (1) The child has been abandoned by the parent in the sense that the parent has failed to maintain a reasonable degree of interest, concern or responsibility as to the welfare of the child; or (2) the parent of a child who has been found by the superior court to have been neglected or uncared for in a prior proceeding has failed to achieve such degree of personal rehabilitation as would encourage the belief that within a reasonable time, considering the age and needs of the child, such parent could assume a responsible position in the life of the child; or (3) the child has been denied, by reason of an act or acts of parental commission or omission, the care, guidance or control necessary for his physical, educational, moral or emotional well-being. Nonaccidental or inadequately explained serious physical injury to a child shall constitute prima facie evidence of acts of parental commission or omission sufficient for the termination of parental rights; or (4) there is no ongoing parent-child relationship, which means the relationship that ordinarily develops as a result of a parent having met on a day to day basis the physical, emotional, moral and educational needs of the child and to allow further time for the establishment or reestablishment of such parent-child relationship would be detrimental to the best interest of the child. The requirement that the department of children and families has made reasonable efforts to reunify the child with the parent shall not apply to terminations of parental rights based on consent or terminations of parental rights where such reasonable efforts at reunification were not possible. If the court denies a petition for *579consent termination of parental rights, it may refer the matter to an agency to assess the needs of the child, the care the child is receiving, and the plan of the parent for the child.”
General Statutes (Rev. to 1993) § 46b-129 (d), as amended by Public Acts 1993, No. 93-91, provides in relevant part: “Upon finding and adjudging that *581any child or youth is uncared-for, neglected or dependent, the court may commit him to the commissioner of children and families for a maximum period of eighteen months, unless such period is extended in accordance with the provisions of subsection (e) of this section, provided such commitment or any extension thereof may be revoked or parental rights terminated at any time by the court, or the court may vest such child’s or youth’s care and personal custody in any private or public agency which is permitted by law to care for neglected, uncared-for or dependent children or youth or with any person found to be suitable and worthy of such responsibility by the court. ...”
General Statutes (Rev. to 1995) § 17a-112 (d), as amended by Public Acts 1995, No. 95-238, provides: “Except in the case where termination is based on consent, in determining whether to terminate parental rights under this section, the court shall consider and shall make written findings regarding: (1) The timeliness, nature and extent of services offered or provided to the parent and the child by an agency to facilitate the reunion of the child with the parent,; (2) whether the department of children and families has made reasonable efforts to reunite the family pursuant to the federal Adoption Assistance and Child Welfare Act of 1980, as amended; (3) the terms of any applicable court order entered into and agreed upon by any individual or agency and the parent, and the extent to which all parties have fulfilled their obligations under such order; (4) the feelings and emotional ties of the child with respect to his parents, any guardian of his person and any person who has exercised physical care, custody or control of the child for at least one year and with whom the child has developed significant emotional ties; (5) the age of the child; (6) the efforts the parent has made to adjust his circumstances, conduct, or conditions to make it in the best interest of the child to return him to his home in the foreseeable future, including, but not limited to, (A) the extent to which the parent has maintained contact with the child as part of an effort to reunite the child with the parent, provided the court, may give weight to incidental visitations, communications or contributions and (B) the maintenance of regular contact or communication with the guardian or other custodian of the child; and (7) the extent to which a parent has been prevented from maintaining a meaningful relationship with the child by the unreasonable act or conduct of the other parent of the child, or the unreasonable act of any other person or by the economic circumstances of the parent.”
General Statutes (Rev. to 1995) § 17a-112 (e) provides: “Any petition brought by the commissioner of children and families to the superior court, pursuant to subsection (a) of section 4Gb-129, may be accompanied by or, upon motion by the petitioner, consolidated with a petition for termination of parental rights filed in accordance with this section with respect to such child, notwithstanding that such child has not been committed to the commissioner of children and families. Notice of the hearing on such petitions shall be given in accordance with sections 45a-716 and 45a-717. The superior court, after hearing, in accordance with the provisions of subsection (b) of this section, may, in lieu of granting the petition filed pursuant to section 461)-129, grant the petition for termination of parental rights as provided in section 45a-717.”
The attorney for the respondent mother did not join in the motion to strike the psychologist’s testimony nor does her brief raise the denial of that motion as a ground for a new trial. Nevertheless, our order for a new trial because of the denial of that motion applies to the respondent mother as well as the respondent father. They were both adversely affected by the ruling that we conclude was incorrect. Neither the father nor the mother sought to retain parental rights apart from the other. It would be incongruous to order a new trial for the father only.
Rule 706 (a) of the Federal Rules of Evidence provides that an expert witness appointed by the court “shall be informed of the witness’ duties by the court in writing, a copy of which shall be filed with the clerk, or at a conference in which the parties shall have opportunity to participate. . . .” The record in this appeal does not reveal what instructions the psychologist appointed by the court received concerning his duties. Practice Book § 25-33, which requires an expert witness appointed by the court to be informed of his duties by the court either in writing or at a conference in which the parties have a right to participate, did not become effective until after the trial of the present case.