Martin Carr was 15 when he raped, beat, and stabbed a young woman in Harbor Point, leaving her so battered she could not recognize her own face in the mirror.
Carr was not caught, and over the next two decades he appeared to become less violent. He got his GED, started a relationship, became a father. But he was arrested for drug distribution several times, and DNA collected in one of those cases led him to be charged in the 1998 rape.
Last week Carr, now 31, begged for leniency, imploring a Suffolk Superior Court judge to save his two sons from "growing up without their father." His sentence: 8 to 10 years, half what prosecutors sought.
Carr's case points to an intricacy in Massachusetts law: Juvenile court judges cannot preside over the trial of an adult charged for something he did as a child or as a teenager. When Carr went to trial, he no longer had access to the juvenile court system, where an offender's age is taken into account and often results in a lighter sentence.
"It's unfair no matter how you look at it," said retired Juvenile Court judge Gail Garinger, who is now the state's child advocate. "When there is this vast gap in time, there really is no way to do as well by the victim and the perpetrator."
But recent decisions by the Supreme Court and the Massachusetts Supreme Judicial Court have suggested that judges look more closely at the age defendants were when they committed an offense.
In 2012, the Supreme Court struck down automatic sentences of life without parole for juveniles, declaring them unconstitutional. The state Supreme Judicial Court went a step further in 2013, ruling that juveniles should not be sentenced to life without parole — automatic or not. Both courts based their decisions largely on the growing scientific evidence that because of brain development, juveniles are less culpable than adults for their actions, even in cases of extreme violence.
Advocates for lighter sentences for juvenile defendants say the rulings should factor into a judge's decision-making even when life sentences aren't in play and when many years have passed between the crime and a conviction.
"The cases refer to what we now know about the adolescent brain, that for many young offenders impulse control is not completely developed," Garinger said. "Taking such factors into account should . . . lead to a recognition that young offenders often mature and can develop into persons who will not pose a threat to public safety."
But Suffolk District Attorney Daniel F. Conley said in Carr's case, the viciousness of the crime should have outweighed the issue of age.
"We appreciate the defendant's age at the time of the offense," he said. "But we can't lose sight of the sheer brutality of his crime. It was a particularly vicious sexual assault that could have very well have ended as a murder."
In September 1998, the victim was 19 and starting her second year at college. She had gone to a party in the Harbor Point development in South Boston with her brother and some friends. At 2 a.m. her brother left, but she stayed for another two hours.
When she left, she was intoxicated and ran into two teenage boys who had been at the party. They asked her whether she wanted to join them at their place in Harbor Point.
As they climbed the concrete stairwell to the apartment, one of them, a short teenager in a baseball cap, grabbed her and slammed her head against the wall. He pummeled her face and body, then took off her jeans. After he raped her, he began beating her again as his friend looked on.
She begged the friend to help but he did nothing as her attacker dragged her under the stairwell and began slashing at her body and neck. He stabbed her 20 times and slit her throat, then walked away.
The woman played dead and when she was sure they were gone, she ran toward Morrissey Boulevard, where a group of people found her and called an ambulance.
At the hospital, a rape examination was done. Police showed her booking photos of youths who resembled her description of her attacker, but the victim did not recognize any of them.
A year after the attack, Carr was convicted of armed robbery and gun possession. After that, however, he has no other major arrests for violence on his record.
The rape case went cold until 2010, when Boston police learned that the DNA of a man convicted and incarcerated in Maine for marijuana distribution matched that sample taken from the rape victim.
Suffolk prosecutors initially had Carr indicted as a youthful offender on one count of aggravated rape and one count of assault with intent to murder, but the Supreme Judicial Court ruled that defendants like Carr have a right to go before a juvenile court judge for a "transfer hearing." During those hearings, the judge hears evidence on the case and decides whether the case should be dismissed or if there is enough probable cause to show that it is in the interest of public safety for the case to move to Superior Court.
In 2012, a juvenile court judge ruled Carr should be tried in Superior Court.
In June 2014, the case finally went to trial. The jury dismissed the assault charge on the basis that the statute of limitations had run out, and declared they were deadlocked on the rape charge.
Last month, a separate jury convicted Carr of aggravated rape.
At his sentencing, Carr acknowledged he made mistakes as a teen, but insisted he was innocent of the rape.
"That's not who I am," he said. "That's not who I was even as a juvenile."
The victim, now 35, sat in the courtroom, shaking her head. She waited for him to turn and say something to her but he never did.
Lynn Feigenbaum, who prosecuted the case, said Carr still showed no remorse and asked for a sentence of 20 to 25 years.
But defense lawyer John MacLachlan said Carr's age at the time of the crime had to be considered in the sentence. He asked for 3 to 5 years.
MacLachlan told Judge Garry V. Inge: "I don't see how we can look through the eyes of a teenager and the acts of a teenager and say, well, because we didn't get the evidence and because we didn't prosecute you until 15 years later, you're therefore an adult."
Days later, the victim said she was at peace with the sentence. Married now, she teaches preschool and is thinking of having children.
"I feel vindicated," she said. "He has time. He has to sit there."
But she disputed the notion that in the years that followed the attack, Carr changed. "If you're going to do something like that it doesn't matter what age you are," she said. "You're just a bad person."
Maria Cramer can be reached at mcramer@globe.com. Follow her on Twitter @globemcramer.