WHITE RIVER JUNCTION — A 30-year-old Hartford man has pleaded guilty to a sex offense that occurred more than 13 years ago, concluding a three-year prosecution in which the state’s case was undercut after a judge found that police investigators had violated the defendant’s constitutional rights.

Justin Chamberlin, who was 16 or 17 at the time of the alleged offense, pleaded guilty to one count of sexual assault and no contest to a charge of unlawful restraint in Windsor County Superior Court on Tuesday.

He will receive a deferred sentence of zero to five years in prison, all suspended, and 10 years probation.

Under a deferred sentence, a court conviction drops from the record if the defendant successfully completes probation.

Chamberlin had been charged with four felony counts of sexual assault plus one felony count of lewd and lascivious conduct in 2020.

The offenses had allegedly occurred in 2009 and 2010 against a victim who was 6 and 7 years old at the time, according to court documents.

An additional charge of unlawful restraint was subsequently added.

The alleged offenses occurred when Chamberlin and the victim were attending an ox-pulling event and then again a few months later at Chamberlin’s family’s residence in Pomfret, court documents said.

The incidents came to light a decade later when the victim, then about 16 years old, informed his family about the assaults, according to investigators.

The charges were brought against Chamberlin in Superior Court because, by the time the state had learned about the allegations, the defendant was no longer a minor and therefore ineligible to be prosecuted in juvenile court.

The state’s prosecution was dealt a blow earlier this year, however, when statements Chamberlin made to police officers were deemed inadmissible because he had not been properly informed of his Miranda rights before he was questioned.

Chamberlin, through his attorney at the time, Sandra Nelson, of Norwich, filed a motion in Windsor court last year seeking to suppress the statements.

Chamberlin said that in three separate interrogations by police he wasn’t warned of his Miranda rights — which inform a suspect that, among other things, he or she is not required to answer questions under arrest or while “in custody,” according to the motion.

The motion detailed how plain-clothed police officers twice showed up at the Upper Valley Haven shelter in White River Junction, where Chamberlin was residing, to question him about the alleged assaults of a decade earlier.

A third interrogation occurred while Chamberlin was being detained in a holding cell in Westminster, Vt., in connection with an unrelated arson investigation.

In response to Chamberlin’s motion, state prosecutors did not dispute that police had not warned of him of his Miranda rights before questioning him.

But the state maintained that in the context of the interviews in which Chamberlin participated, a “reasonable person would not have believed that they were under the functional equivalent of arrest” as is need to trigger a Miranda warning requirement.

As for the third interview in the holding cell, the state said that Chamberlin had waived his Miranda rights in regard to the arson investigation when the conversation “transitioned” into Chamberlain talking about the alleged sex abuse.

“At no point did (Chamberlin) appear to be engaging in a non-consensual discussion” nor did he invoke his Miranda rights “that had just been explained to him a short time prior,” the state argued.

Superior Court Judge John Treadwell wasn’t persuaded by the state’s counterarguments when he found in the defendant’s favor in his ruling in February.

In a 16-page analysis and opinion citing case law, Treadwell found that Chamberlin had been “subjected to repeated unwarned custodial interrogations” by police officers and therefore the self-incriminating statements he gave were “involuntary.”

“The three statements were obtained in violation of the defendant’s constitutional rights,” Treadwell wrote, finding that there was a “factual predicate of (Chamberlin’s) uncontroverted argument that the statements were involuntary.”

As part of his deferred sentence — meaning the defendant will serve no time in prison as long as he abides by the conditions of his probation — Chamberlin must engage in sex offender treatment and have no contact with any minors under the age of 16, according to court documents.

Chamberlin, the father of two children, will have to register as a sex offender during his probationary period, but if he successfully completes probation then his name will be removed from the registry.

Treadwell ordered a pre-sentencing report to be prepared by the Department of Corrections in preparation for a formal sentencing hearing within 75 days.

Contact John Lippman at jlippman@vnews.com.