OPINION
LARSEN, Justice.D.A.R., a juvenile, appeals his judgment of probation for delinquent conduct. He argues that the trial court erred in denying his motion to suppress statements because they were inadmissible as a result of noncompliance with Tex. Fam.Code Ann. § 51.095 and that he therefore was denied his due process rights. We reverse and remand.
Facts
D.A.R. was indicted for one count of delinquent conduct for carrying a firearm on school grounds. He was indicted for one count of delinquent conduct for possessing a firearm with an altered identification number. He initially pleaded not true to each count.
D.A.R. filed a pretrial motion to suppress, urging that at the time statements were made, he was under arrest and that he was deprived of the right to counsel and therefore did not intelligently, understandably, and knowingly waive his right to counsel. He argued that any resulting statements were involuntary, coerced, or enticed from him in violation of his constitutional and statutory rights. A hearing was held on the motion. Officer Jose A. Gonzalez, Jr., a school resource officer, *508was the only witness presented at the hearing.
Officer Gonzalez testified that on November 17, 2000, he was notified by the assistant principal of Riverside Middle School that a student had said that D.A.R. had a weapon. D.A.R. was called to the assistant principal’s office. Before D.A.R. entered the office, he was patted down. The assistant principal also went through D.A.R.’s backpack. No weapon was retrieved. D.A.R. was questioned but denied having any weapon.
D.A.R. was dismissed to return to class. Afterward, approximately fifteen students approached Officer Gonzalez and told him that D.A.R. was in possession of a gun and that they had been hearing that D.A.R. had brought a gun to school for his protection. One of the individuals told Officer Gonzalez that she had seen the gun before school. Although she did not know exactly where the gun was located, she took Officer Gonzalez to the area around a reservoir where the gun might be.
Officer Gonzalez summoned D.A.R. from class. A security guard brought D.A.R. to Officer Gonzalez’s office. Officer Gonzalez again asked D.A.R. about the gun. He told D.A.R. that several students had told him that D.A.R. had a gun and that if D.A.R. had a gun it would be best for him to give it up.
During this second interrogation, a teacher signaled Officer Gonzalez and spoke privately with him. She told him that another student had information about the location of the gun. Officer Gonzalez testified at the hearing that if appellant had refused to speak to him, he would have spoken to the other student; however, he did not then speak to the student. Instead, he continued to speak to D.A.R. because of his need to secure the weapon as soon as possible. The other student was never questioned.
After the interruption, D.A.R. told Officer Gonzalez where the weapon was located and took him to it. The gun was discovered under a tire, approximately 150 feet from the school within the same area where the other student had taken Officer Gonzalez. The gun was not in plain view. D.A.R. was read his Miranda rights1 and placed in custody.
The trial judge denied the motion to suppress based on the belief that the statements were admissible under Tex. Fam. Code Ann. § 51.095(a)(2).2
Thereafter, D.A.R. entered into an agreement to plead true to one count of delinquent conduct based on carrying a firearm in violation of Tex. Penal Code Ann. § 46.02, which was a modified version of the original first count. The second count of delinquent conduct was dropped. D.A.R. was adjudicated delinquent and received supervised probation until his eighteenth birthday for the offense.
D.A.R. brings one point on appeal of the judgment and seeks reversal and remand.
Right to appeal
A juvenile appellant is given the right to appeal under Tex. Fam.Code Ann. § 56.01(n), which states:
A child who enters a plea or agrees to a stipulation of evidence in a proceeding held under this title may not appeal an order of the juvenile court entered un*509der Section 54.03, 54.04, or 54.05 if the court makes a disposition in accordance with the agreement between the state and the child regarding the disposition of the case, unless:
(1) the court gives the child permission to appeal; or
(2) the appeal is based on a matter raised by written motion filed before the proceeding in which the child entered the plea or agreed to the stipulation of evidence.
Tex. Fam.Code Ann. § 56.01(n) (Vernon Supp.2002). Here, the trial court gave appellant implied permission to appeal his judgment. Moreover, appellant brings appeal based on the denial of his motion to suppress, which was filed pretrial, and it was only after appellant’s motion to suppress was denied that his agreement with the State arose. Therefore, this appeal is appropriate.
Admissibility of statements
Under Tex. Fam.Code Ann. § 51.095, certain requirements must be met in order for a statement from a juvenile to be admissible at trial. Tex. Fam.Code Ann. § 51.095 (Vernon Supp.2002); see also In re Gault, 387 U.S. 1, 55, 87 S.Ct. 1428, 1458, 18 L.Ed.2d 527 (1967) (holding that the right against self-incrimination available to adults is also applicable in the juvenile context), cited in In re L.M., 993 S.W.2d 276, 287 (Tex.App.—Austin 1999, pet. denied). Here, appellant argues in his sole issue that the requirements of Section 51.095 were not met and that therefore his statements were inadmissible under Tex. Code CRiM. PROC. Ann. art. 38.23. Specifically, appellant argues that he was in custody when the statements were made. As a result, he should have been informed of his rights before he was questioned. Appellant argues that even if he was not in custody when the confession was given, his statements were not made voluntarily. In response, the State argues that appellant was not in custody when the statements were made. The State further contends that the issue of voluntariness and coercion cannot be raised because appellant failed to preserve those claims in the lower court. If appellant was in custody when he was questioned by Officer Gonzalez, he was entitled to certain protections. Tex. Fam. Code Ann. § 51.095(d) (Vernon Supp.2002). Therefore, the question central to this appeal is if appellant was in custody. We discuss this first.
Standard of review
In a suppression hearing, the trial court is the sole finder of fact. Pace v. State, 986 S.W.2d 740, 744 (Tex.App.—El Paso 1999, pet. ref'd). The trial judge may believe or disbelieve any of the evidence presented. Id. at 744. The totality of circumstances is considered in determining whether the trial court’s findings are supported by the record and, absent a clear abuse of discretion, the reviewing court does not disturb those findings. Brewer v. State, 932 S.W.2d 161, 166 (Tex.App.—El Paso 1996, no pet.). If there are no findings of fact, the reviewing court presumes the trial court found the facts necessary to support its ruling, so long as those findings are supported by the record. State v. Fecci, 9 S.W.3d 212, 219 (Tex.App.—San Antonio 1999, no pet.). Therefore, the evidence adduced at the suppression hearing is reviewed in the light most favorable to the trial court’s ruling. Brewer, 932 S.W.2d at 166.
In contrast, mixed questions of law and fact not turning on credibility and demeanor are subject to de novo review. Guzman v. State, 955 S.W.2d 85, 89 (Tex.Crim.App.1997). Because the issue of custody does not turn on the credibility or demeanor of witnesses, the determination *510of whether an appellant was in custody at the time he gave statements is one such mixed question reviewed de novo. Jeffley v. State, 38 S.W.3d 847, 853 (Tex.App.—Houston [14th Dist.] 2001, pet. ref'd).
Was appellant in custody?
The Court of Criminal Appeals, citing Stansbury v. California, 511 U.S. 318, 322, 114 S.Ct. 1526, 1528-30, 128 L.Ed.2d 293, 298-99 (1994), stated that a person is in custody if “under the circumstances, a reasonable person would believe that his freedom of movement was restrained to the degree associated with a formal arrest.” Dowthitt v. State, 931 S.W.2d 244, 254 (Tex.Crim.App.1996).3 This is the standard of review that appellant relies on.
The State refers to the standard utilized in In re M.R.R., Jr., 2 S.W.3d 319 (Tex.App.—San Antonio 1999, no pet.), to determine whether appellant was in custody at the time the statements were made. That standard employs a two-step analysis, set forth by Stansbury and another U.S. Supreme Court case, Thompson v. Keohane, 516 U.S. 99, 116 S.Ct. 457, 133 L.Ed.2d 383 (1995). The first prong examines the circumstances surrounding the interrogation in deciding whether there was a formal arrest or restraint to the degree associated with a formal arrest. In re M.R.R., Jr., 2 S.W.3d at 323. Under the second prong, the court considers whether a reasonable person would have felt he or she was at liberty to terminate the interrogation and leave. Id.
Arguably, both standards allow for a consideration of the totality of circumstances and, we believe, implicit within that, the age of the juvenile. However, neither standard allows for an explicit consideration of the age of the juvenile. The standard that allows for such a consideration was set forth by the Austin Court of Appeals in In re L.M. See also Jeffley, 38 S.W.3d at 855 (adopting the standard of In re L.M.); In re E.M.R., 55 S.W.3d 712, 722-24 (Tex.App.—Corpus Christi 2001, no pet.) (Yanez, J., dissenting). The Austin court, in discussing the standard to be applied with respect to determining whether a juvenile is in custody, cited caselaw from other states that adopted the age of the juvenile as a specific consideration. The court then concluded that it is appropriate for Texas courts to also consider the age of the juvenile. In re L.M., 993 S.W.2d at 288-89. It then adopted the following inquiry: “whether, based upon the objective circumstances, a reasonable child of the same age would believe her freedom of movement was significantly restricted.” Id. at 289. The court was quick to note that although it incorporated an explicit consideration of age in its standard, its holding did not conflict with earlier Texas cases. Id. And, we note that the standard is similar to the Stansbury standard but includes an explicit consideration of the age of the juvenile.4
We too believe that a consideration of the age of the juvenile is appropriate. *511Furthermore, we believe that such a consideration is consistent with the stated purpose of the Juvenile Justice Code, which is, in part, to assure that juveniles receive a fair hearing and that their rights are recognized and enforced, Tex. Fam. Code ANN. § 51.01(6) (Vernon 1996).
We believe the facts here establish that a reasonable thirteen-year-old would have believed he was in custody. We are aided in our inquiry by Dowthitt, which gave several factors that might be considered in determining whether an individual was in custody. Among them, the court may consider whether there was probable cause to arrest at the time of questioning; the subjective intent of the police; the focus of the investigation; and the subjective belief of the juvenile. 931 S.W.2d at 254; see also In re V.P., 55 S.W.3d 25, 31 (Tex.App.—Austin 2001, pet. denied) (applying the Dowthitt factors to a situation involving a juvenile). But, the subjective elements are only relevant to the extent that they are manifested in words or actions, Dowthitt, 931 S.W.2d at 254, as the test for custody relies solely on objective circumstances, id. Even a determination of probable cause is based on such an expression. Id. at 255.
First, there was probable cause to arrest appellant. Officer Gonzalez testified that at least fifteen students had told him appellant had a gun. He felt that the statements could not be mere coincidence. At the very least, Officer Gonzalez had probable cause to arrest appellant after appellant admitted that he had a gun and had left it close to the school grounds. Tex. Fam.Code ANN. § 52.01(a)(3) (Vernon 1996); Lanes v. State, 767 S.W.2d 789, 800 (Tex.Crim.App.1989); Vasquez v. State, 739 S.W.2d 37, 44 (Tex.Crim.App.1987) (holding that an officer may make a warrantless arrest if he has knowledge based upon reasonably trustworthy information that would warrant a reasonable and prudent person in believing that the person has committed or is committing a crime). At this point, Officer Gonzalez testified, appellant was no longer free to leave because he was under investigation.
A reasonable thirteen-year-old child in appellant’s position, moreover, would have become aware of Officer Gonzalez’s probable cause to arrest him. Appellant had been called to the assistant principal’s office for the first interview, where the assistant principal, security officer, and Officer Gonzalez were present. Appellant had been released from the initial interview, but then the uniformed security guard escorted appellant from class to Officer Gonzalez’s office for a second interview, during which only Officer Gonzalez and appellant were present. The door was closed, leaving appellant alone with an armed, uniformed police officer who confronted him with allegations by numerous students that appellant had a gun. During the initial interview, appellant was told that it was rumored he had brought a gun, but during the second interview, Officer Gonzalez told him that fifteen students had told him appellant had a gun. Officer Gonzalez pressed appellant to tell him where the gun was, telling appellant that it was too much of a coincidence that all of the students had told him appellant had a gun and that it would be best for appellant to confess. And certainly, after appellant made his confession, he would have realized Officer Gonzalez’s probable cause to arrest him, given that the incriminating nature of his statement would substantiate Officer Gonzalez’s probable cause. See Dowthitt, 931 S.W.2d at 255.
Officer Gonzalez testified that he did not question the student the teacher had told him about because he was worried about that child’s safety. Specifically, he was *512concerned about any retaliation that might come as a result of the child acting as an informant. The second student would have been needed if appellant had been uncooperative and the student had helped locate the gun instead. Thus, appellant was the focus of the investigation, and the evidence suggests that the investigation was more than merely an attempt to secure the safety of the students; the evidence suggests that the investigation became criminal in nature and that not only was Officer Gonzalez attempting to secure the safety of the students, but he was also looking to the future criminal proceedings against appellant.
Officer Gonzalez also testified that he did not consider appellant to be in custody during either the first or second inquiries and testified that appellant was not Mir-andized before the weapon was found because appellant was not then under arrest. During the second inquiry, in which only he and appellant were present, Officer Gonzalez believed that appellant was free to leave. Appellant was not handcuffed and the door was not locked.
But, neither was appellant told that he could leave. The door, although unlocked, was closed. Officer Gonzalez testified if appellant had been uncooperative, he would not have been allowed to leave; rather, appellant would have been required to stay in Officer Gonzalez’s office while the other student was questioned.
Appellant was first questioned in the assistant principal’s office by the assistant principal. During the second inquiry, appellant was taken to the police officer’s office by a uniformed security guard. Appellant was unaccompanied when he was questioned, and he was not told that he could leave or call an adult to join him. We believe the facts were such that appellant would have believed his freedom of movement was significantly restricted. Cf. In re V.P., 55 S.W.3d at 33 (holding a juvenile not in custody where the juvenile, who brought a gun to school, was questioned in the assistant principal’s office, because the juvenile was not questioned by the police officer and the officer was not present during the inquiry and as a result the juvenile was not the subject of a criminal investigation).
It was not until appellant was confronted with the statements the other students had made that he confessed to Officer Gonzalez that he had a gun and that he had left it close to the school grounds. Officer Gonzalez testified: “I told him I had information that he had the gun and it was too much of a coincidence that 15 students were telling me about his gun.” Officer Gonzalez told appellant that “it would be best for [appellant]” if appellant told him about the gun. Even if appellant was not initially under arrest when he was called into Officer Gonzalez’s office, the interrogation escalated into an arrest. See Jeffley, 38 S.W.3d at 857 (holding that when a suspect that was not previously in custody was pressed by the questioning officer for a truthful statement the situation escalated into a custodial interrogation and the appellant could have concluded that her freedom was inhibited significantly as to the extent of a formal arrest); Dowthitt, 931 S.W.2d at 255 (“[T]he mere fact that an interrogation begins as noncustodial does not prevent custody from arising later; police conduct during the encounter may cause a consensual inquiry to escalate into custodial interrogation.”).
In light of the circumstances, we believe that appellant was in custody when his statements were made. Although the events here occurred in quick succession, there was sufficient time for Officer Gonzalez to realize that appellant came into custody and should have been given proper warnings. Yet, Officer Gonzalez issued no *513warnings to appellant and instead asked appellant to take him to the gun.
Appellant’s statements were oral. Therefore, the admissibility of appellant’s statements is guided by Tex. Fam.Code Ann. § 51.095(a)(5). Among its several requirements, a statement is only admissible if the child is given warnings by a magistrate before the statement is made and the child knowingly, intelligently, and voluntarily waives each right stated in the warning. Tex. Fam.Code Ann. § 51.095(a)(5)(A) (Vernon Supp.2002). The appropriate warnings were not administered to appellant here. Accordingly, we believe the trial court ruled incorrectly in concluding that appellant’s statements were admissible under Section 51.095(a)(2).
Harm
We consider next whether the trial court’s error was harmful under Tex. R.App. P. 44.2, which governs error in criminal cases. Error may be constitutional in nature, and the reviewing court must reverse the judgment of the lower court unless it determines beyond a reasonable doubt that the error was harmless. Tex.R.App. P, 44.2(a). If the error is non-constitutional, it must be disregarded unless it affects substantial rights. Tex. R.App. P. 44.2(b); Johnson v. State, 43 S.W.3d 1, 4 (Tex.Crim.App.2001). The improper admission of a statement in response to custodial interrogation implicates the constitutional right against self-incrimination. See Tex.Code CRiM. PROC. Ann. art. 38.23 (Vernon 1979 & Supp.2002); In re L.M., 993 S.W.2d at 287 (relying on In re Gault in applying the constitutional right against self-incrimination to children). We therefore employ the harm analysis mandated by Tex.R.App. P. 44.2(a).
This Court stated in Villalobos v. State, 999 S.W.2d 132 (Tex.App.—El Paso 1999, no pet.), “Essentially, where constitutional error is shown, the burden is on the State to come forward with reasons why the error is harmless.” Id. at 136. We will reverse unless the record establishes beyond a reasonable doubt that the admission did not contribute to the conviction.
In the present case, we cannot find beyond a reasonable doubt that the trial court’s denial of the motion to suppress did not affect appellant’s decision to plead guilty and the resulting conviction. The error arose from appellant’s interrogation while in custody, which violated his rights under the Juvenile Justice Code and his constitutional rights against self-incrimination. Likely, any juror would have placed great weight on the statements that appellant made. And the probable implication of the error was appellant’s decision to plead guilty, subsequent to the denial of his motion to suppress. Thus, we conclude that error was harmful.
Because we find that the appellant was not properly warned in accordance with Section 51.095, we need not discuss the voluntariness of appellant’s statement.
We sustain appellant’s point.
Conclusion
We reverse the judgment of the trial court and remand for further proceedings.
McCLURE, J., dissenting.
. Miranda v. Arizona, 384 U.S. 436, 444, 86 S.Ct. 1602, 1612, 16 L.Ed.2d 694 (1966).
. Under Section 51.095(a)(2), the statement of a child is admissible in evidence if the statement is made orally and the child makes a statement of facts or circumstances that are determined to be true and tend to establish his guilt. Tex. Fam.Code Ann. § 51.095(a)(2) (Vernon Supp.2002).
. We rely on criminal cases in this analysis because, as we noted in In re R.S.C., 940 S.W.2d 750 (Tex.App.—El Paso 1997, no pet.), "[ajlthough juvenile delinquency proceedings are considered civil proceedings, they are quasi-criminal in nature. The juvenile is guaranteed the constitutional rights an adult would have in a criminal proceeding because the juvenile delinquency proceedings seek to deprive the juvenile of his liberty.'' Id. at 751 (citations omitted).
. See also In re S.A.R., 931 S.W.2d 585 (Tex.App.—San Antonio 1996, pet. denied), and In re V.M.D., 974 S.W.2d 332 (Tex.App.—San Antonio 1998, no pet.), which In re L.M. cites as using the reasonable person standard of Stansbury while impliedly considering the age of the defendant in reviewing the circumstances in each case. 993 S.W.2d at 288.