When Prentis Cordell Jackson learned in 2006 that he would never again know freedom, the convicted murderer, then 17, felt a lot of different things. Numb. Angry. Sad.

"I was old enough to go spend the rest of my life in prison, but I wasn't old enough to go buy a pack of cigarettes," he said during an interview last spring at Oak Park Heights Correctional Facility.

On Monday, the U.S. Supreme Court ruled Jackson and more than 2,100 other inmates who committed murders as teenagers must be considered for parole or given a new sentence, no matter how long ago the crime occurred. The ruling greatly expands the court's 2012 landmark Miller vs. Alabama decision involving a 14-year-old boy that said sentences of mandatory life without parole for juveniles was unconstitutional and amounted to cruel and unusual punishment. With Monday's action, the decision extends to juveniles sentenced before the 2012 ruling.

Minnesota has eight juvenile killers in prison under its "heinous crimes" statute. However, some states such as Pennsylvania and Michigan have a combined 900 cases that will require judicial review.

"The ruling has a significant impact across the country," said Perry Moriearty, a University of Minnesota law professor and co-director of the Child Advocacy and Juvenile Justice Clinic. Moriearty and William Mitchell law Prof. Bradford Colbert are representing convicts in two cases. "For states sitting on their hands on these cases, they now have to do something." Moriearty said.

The U.S. Supreme Court ruled 6-3 in the case of Henry Montgomery, who has been in prison more than 50 years since he killed a sheriff's deputy as a 17-year-old in Baton Rouge, La., in 1963. Until Monday's ruling, it was unclear whether that 2012 decision was retroactive for juveniles already serving their life sentences.

In the majority opinion, Justice Anthony Kennedy wrote that states do not have to go so far as to resentence killers serving life terms. Instead, the states can offer parole hearings with no guarantee of release.

Minnesota doesn't have a parole board system and offers the possibility of parole only after two-thirds of a sentence has been served. The decision does not expressly forbid judges from sentencing teenagers to a lifetime in prison. But the Supreme Court has previously said such sentences should be rare, and only for the most heinous crimes.

This month, Hennepin County's chief judge reduced part of the mandatory murder sentence of Mahdi Hassan Ali, who killed three people in a small Minneapolis grocery store. Ali, now 23, will be eligible for parole after 30 years for one of the murders. But his original punishment for the two other victims was life with parole after 30 years — to be served consecutively, meaning that Ali would be older than 100 before his possible release.

It's possible his case could be reviewed again because he is serving a "functional death-in-prison sentence," Moriearty said. One of her clients, Brian Flowers, learned Friday that his case received a resentencing hearing. He and another teenager, Stafon Thompson, stabbed a woman more than 100 times as her 10-year-old son watched, then killed the boy by smashing a TV onto his head.

Hennepin County Attorney Mike Freeman said he had previously reviewed the eight cases, five of which happened in his jurisdiction. He plans to again look at the cases and figure out a way to find a fair and appropriate resolution. Ali's resentence of a chance at parole after 30 years will be the benchmark, he said.

"When I did my review several years ago, these were some of the most hideous murders you can think of," he said. "We will look at how long they've been in prison and the circumstance surrounding the crime. They would have had to [have] earned their parole."

Jackson, who was 26 when he was interviewed last spring, claimed he had nothing to do with the 2006 gang slaying of 15-year-old Michael "Tony" Bluntson.

"Whether I did something or not, I don't even think the same way that I thought when I was 17," he said. "I don't even think the same way I did when I was 21, let alone 17."

Flowers, who also was interviewed in prison last spring, said when the first of the Supreme Court decisions was handed down in 2012, he felt his prayers were answered. Flowers believes he deserves to be released. Asked when, he pauses.

"I've thought about it, but I can't tell you I deserve to get out tomorrow. I'm not gonna sit here and say that because I don't know. But I know I deserve to get out one day soon," he said.