Petitioners seek review of trial court orders denying their pretrial motions to appoint an expert to perform a sexual deviancy evaluation at public expense. A commissioner of this court denied Hermanson's motion for discretionary review and Hermanson has since moved to modify that ruling. Heath's motion for discretionary review has been referred to this panel for determination on the merits. In both cases the only issue presented is whether CrR 3.1(f) requires the State to appoint an expert to perform a sexual deviancy evaluation of an indigent defendant so the defendant may be able to take advantage of the special sex offender sentencing alternative (SSOSA). We grant Hermanson's motion to modify, accept review in both cases, consolidate the two appeals, and consider the merits on an accelerated basis pursuant to RAP 18.12.1
The merits of the two cases will be discussed separately.
Hermanson
The material facts in this case are succinctly set forth in the commissioner's ruling denying discretionary review:
*452Hermanson is charged in King County Superior Court with three counts of rape of a child in the first degree. He is indigent and represented by a public defender. He has entered a plea of not guilty and trial in the matter is currently scheduled for December 4, 1991.
Hermanson has no prior felony convictions. His presumptive range, if convicted as charged, is 72 to 96 months. He would therefore be statutorily ineligible to receive a sentence pursuant to the Special Sex Offender Sentencing Alternative (SSOSA). RCW 9.94A.120(7). However, the State has indicated that it will amend the present charges in a manner to make Hermanson eligible for a SSOSA if he first receives a sexual deviancy evaluation and is found amenable to treatment. Hermanson wishes to take advantage of this offer but alleges he cannot afford the cost of an evaluation.
Hermanson therefore moved for a trial court order allowing such an evaluation at public expense. The cost of such an evaluation is approximately $450. The trial court refused the request, indicating that CrR 3.1(f) authorizes public expenditures for an adequate defense but not so that a defendant may take advantage of a plea bargain.
Hermanson, an indigent defendant, argues that the trial court erred in refusing to authorize the expenditure of public funds for the sexual deviancy evaluation under CrR 3.1(f)(1), which provides:
Counsel for a defendant who is financially unable to obtain investigative, expert, or other services necessary to an adequate defense in the case may request them by a motion to the court.
"This rule incorporates constitutional requirements by recognizing that funds must be provided where necessary to an adequate defense." State v. Kelly, 102 Wn.2d 188, 200, 685 P.2d 564 (1984); State v. Garcia, 57 Wn. App. 927, 936, 791 P.2d 244, review denied, 115 Wn.2d 1010 (1990). The decision of whether an indigent defendant is entitled to the assistance of an expert lies within the sound discretion of the trial court. State v. Garcia, supra. As the court stated in State v. Aamold, 60 Wn. App. 175, 177, 803 P.2d 20, review denied, 117 Wn.2d 1016 (1991),
Under CrR 3.1(f), an indigent defendant is entitled to the assistance of an expert witness only if such services are necessary to an adequate defense. State v. Barnes, 58 Wn. App. 465, 472, 794 P.2d 52, review granted, 115 Wn.2d 1022 (1990)[, affirmed, 117 Wn.2d 701, 818 P.2d 1088 (1991)]. Whether the *453services of an expert are "necessary" within the meaning of this rule is committed to the sound discretion of the trial court, reversible only on a showing of substantial prejudice.
The State asserts that the trial court's decision denying Hermanson's request for appointment of an expert to perform a sexual deviancy evaluation at public expense did not constitute an abuse of discretion. The State relies primarily on State v. Melos, 42 Wn. App. 638, 713 P.2d 138, review denied, 105 Wn.2d 1021 (1986).
In Melos, an indigent defendant assigned error to the trial court's refusal to authorize the expenditure of public funds for a psychiatric examination. Citing State v. Tuffree, 35 Wn. App. 243, 666 P.2d 912, review denied, 100 Wn.2d 1015 (1983), the Melos court held that the evaluation was not necessary to provide the defendant with an adequate defense under CrR 3.1(f) "since he had already pleaded guilty without a trial." State v. Melos, supra at 641.
In Tuffree, the trial court denied the defendant's request for the appointment of an expert at public expense to provide a psychiatric examination at his sentencing. The Tuffree court upheld the decision of the trial court, noting "that the opinion of a professional psychiatrist was not sought in aid of defendant's defense to the crime charged." State v. Tuffree, supra at 249.
Hermanson argues that the phrase "adequate defense" in CrR 3.1(f) should not "be read so narrowly as to deny indigent clients the right to plea bargain and take advantage of favorable plea offers where the indigent must first do some act that costs money." We agree. This case draws a clear distinction between the plea and sentencing phases of a criminal prosecution.
In this case the State, as part of the plea negotiations, has offered to restructure the charge against Hermanson so that he will be eligible for the special sex offender sentencing alternative (SSOSA) under RCW 9.94A 120(7). The SSOSA eligibility requirements mandate that the defendant have no prior convictions for a sex offense, RCW 9.94A-.120(7)(a)(i), that he or she be sentenced to a term of total confinement "of more than one year but less than six years," *454RCW 9.94A.120(7)(c), and not be presently charged with a violation of RCW 9A.44.050 (second degree rape) or a serious, violent, sex offense, RCW 9.94A.120(7)(a)(i).
It is undisputed that Hermanson is not currently eligible for SSOSA. Although he is a first-time sex offender, Hermanson, as presently charged, has a presumptive sentence range of 72 to 96 months. The low end of that sentence range still exceeds the maximum sentence level permitted under SSOSA. In order to meet the eligibility requirements of the statute, the State would have to either drop one of the three charges currently pending against Hermanson or charge him with a lesser offense. By agreeing to restructure the charge against Hermanson, the State has offered him a real incentive to obtain a sexual deviancy evaluation. It is undisputed that the State's offer is contingent upon the defendant's first receiving a sexual deviancy evaluation and being found amenable to treatment. The offer creates a tangible link between the evaluation and matters taking place at the plea negotiations. The request for a sexual deviancy evaluation is therefore not tied solely to matters of sentencing.
The law recognizes exculpatory as well as nonexculpatory defenses. Plea bargained immunity is a nonexculpatory defense and is discussed by one commentator as follows:
Plea bargained immunity arises after the consummation of a plea agreement under which the state either drops pending charges or promises to forego prosecution of an offense not yet charged, in return for a plea of guilty to a lesser or remaining offense. Almost ninety-five percent of all criminal cases are concluded by the entry of a plea of guilty, and a large portion of these pleas are the result of plea negotiations. In spite of their widespread use, plea negotiations were at one time secretive and informal, and neither party was effectively bound by the agreement. Today such agreements, although often criticized, are a formalized part of the criminal justice system; if a valid plea agreement is consummated, it binds all parties, and where the agreement involves a promise to forego prosecution, it provides the defendant with an enforceable immunity from such prosecutions.
(Footnotes omitted.) 2 P. Robinson, Criminal Law Defenses § 206, at 489 (1984). Since the State's plea offer in this case *455would actually reduce Hermanson's liability for his criminal conduct, the availability of the evaluation may be a significant aid in preparing Hermanson's "defense" to the offenses charged. Under the circumstances, the trial court abused its discretion in denying Hermanson's request for appointment of an expert to perform the sexual deviancy evaluation under CrR 3.1(f).
Hermanson's motion to modify is granted, and the decision of the trial court is reversed.
Heath
Heath has been charged with one count of child molestation in the third degree and two counts of rape of a child in the third degree. The charges arose from incidents which occurred during the spring of 1991, in which Heath allegedly had repeated sexual intercourse with the 14-year-old babysitter of his children. Heath sought a sexual deviancy evaluation by a trained therapist at public expense. By notation ruling dated December 19, 1991, the trial court denied the motion, holding:
The defendant's request for a sexual deviancy evaluation for the possible use thereof at the time of sentencing is denied. CrR 3.1(f) authorizes the Court to expend funds when it is requested for "an adequate defense" not for sentencing. St. v. Aamold, 60 Wn. App. 175.
RCW 9.94A.120(f) [sic] authorizes an examination after conviction. *464assessed under the authority of RCW 49.17.180 and shall state that the employer has fifteen working days within which to notify the director that he wishes to appeal the citation or assessment of penalty. If, within fifteen working days from the communication of the notice issued by the director the employer fails to notify the director that he intends to appeal the citation or assessment penalty, and no notice is filed by any employee or representative of employees under subsection (3) of this section within such time, the citation and the assessment shall be deemed a final order of the department and not subject to review by any court or agency." (Italics ours.)
*455Heath contends that the trial court erred in denying his motion for an order allowing a sexual deviancy evaluation by a trained therapist at public expense. Heath's situation is, however, significantly different from Hermanson's. The State here did not agree to reduce the charges pending against Heath. Instead, the State simply agreed to recommend that Heath be sentenced under SSOSA. Because Heath is already eligible for SSOSA, he is seeking the sexual deviancy evaluation solely for sentencing purposes. The evaluation cannot possibly diminish the scope of Heath's criminal liability. Heath's counsel states in an affidavit that the evaluation would be of assistance in representing the *456defendant by ascertaining "the defendant's amenability to community based counseling." Under the circumstances, it should make no difference whether the request for the evaluation occurred before or after Heath was convicted of the charged offenses. Based on the reasoning in Melos and Tuffree, we cannot say that the trial court abused its discretion in refusing to authorize the sexual deviancy evaluation at public expense. The decision of the trial court is affirmed.
In sum, we reverse the denial of Hermanson's pretrial motion for an order appointing an expert to perform a sexual deviancy evaluation at public expense, and affirm the denial of Heath's like motion.
Review denied at 120 Wn.2d 1016 (1992).
"The appellate court may set any review proceeding for accelerated disposition on the judges' motion calendar."