In 1999, Curtis and Catherine Jones were siblings in middle school when they gained notoriety as confessed killers.
For their crime — the fatal shooting of their father's live-in girlfriend, whom police say they grew jealous of — prosecutors sought a distinct punishment: They were, at the time, the youngest children in America to be charged as adults for first-degree murder. He was 12. She was 13.
But on Tuesday, after 16 years behind bars, Curtis is set to become a free man when he is released from a correctional facility in Central Florida. Catherine is scheduled to get out four days later, from another prison over 200 miles away, records show. He is now 29. She is 30.
Little has been shared publicly about their experiences growing up in prison, but psychologists and former incarcerated youth told NBC News that what awaits them in the outside world as adults will be a sort of culture shock.
In a nation where reportedly two-thirds of prisoners are rearrested within three years of their release, what are the prospects for two people who have known only the inside of a cell for most of their lives?
T.J. Parsell, who spent four years in adult prison after holding up a Michigan Fotomat with a toy gun when he was 17, knows the expectations firsthand.
"You feel so lost, and it's scary," said Parsell, now 55 and living in New York City. "Now you're out in the world, and you have to build a life for yourself. It's a shock."
Young prisoners thrown into the adult system already face higher rates of abuse, mental health problems and attempted suicide, said Georgetown University psychology professor Jennifer Woolard.
They also can be separated in adult prisons and isolated to protect them from the general population, she added. The effects can be devastating on young people who are still developing, studies have shown.
"On one hand, you think you're younger and more malleable to what happens to you," Woolard said. "But on the other hand, these are your formative years that are happening in a deprived environment."
In Florida, Curtis and Catherine grew up in a quiet neighborhood of Port St. John where their dad, the elder Curtis Jones, raised them. In this coastal community, the sky seemed limitless - young dreamers only had to tilt their heads to the heavens to watch the rockets launched from Cape Canaveral.
On Jan. 6, 1999, their father's girlfriend, 29-year-old Sonya Nicole Speights, was doing a 500-piece jigsaw puzzle at the dining room table when Catherine used his 9mm handgun to shoot her in the torso, police said. She dropped the weapon as it discharged. Curtis picked it up, emptying the remaining bullets into Speights.
Investigators said they tried to cover up the crime scene as a robbery, and fled into the woods overnight before they were captured.
The motive was simple: "At one time they had been a trio, sort of like the 'Three Amigos,'" Brevard County Sheriff's Agent Todd Goodyear said of the children and their father, the Orlando Sentinel reported at the time. "Now they were a foursome, and they were resentful and jealous of the fact."
But in 2009, Catherine told the FLORIDA TODAY newspaper that there was more to it. She said that she and her brother were being sexually abused by a family member who had stayed at their home. When she told her father and Speights, she said, they didn't believe her.
Investigators later acknowledged they knew of sexual abuse claims, but found no concrete evidence at the time, FLORIDA TODAY reported.
In the newspaper interview, Catherine said that she regretted taking Speights' life. But in prison, she found solace in her solitude.
"At one point I was just so happy to be away," Catherine said. "I know that sounds, like, really messed up, but there was a point where I was just away from all that and I was by myself and I was safe."
Curtis, after being charged, had asked his attorney if he could bring his Nintendo to prison.
The siblings' father stood by their side in court.
He could not be reached for comment, nor could Curtis' and Catherine's mother, Stacie Parks, whose last known address was in Kansas. According to reports, she had let the children live with their father after they broke up.
Two years ago, Catherine married a Navy officer, Ramous Fleming, who had read about her in the news and struck up a pen pal relationship. They were wed in the chapel at the Hernando Correctional Institution in Brooksville, Florida.
Fleming declined to be interviewed by NBC News, he said, out of respect for the family.
Curtis, who got a panther and "MOB" tattoos in prison, has not spoken publicly over the years. Catherine said in 2009 that she had only seen him once since they were incarcerated.
"We're best friends," she said. "Nobody understands what you go through in here except someone else that has been in here."
The siblings in 1999 took a deal with prosecutors, allowing for their release if they pleaded guilty to second-degree murder. As that freedom nears, the siblings will undergo a lifetime of probation.
That's why transitioning with the help of a support system and counseling will be crucial for the pair, said Parsell, the former inmate.
Parsell cleaned up from a period of heavy drinking and drug use when he got out, and eventually went on to become a filmmaker and wrote a memoir about the sexual abuse he suffered as a juvenile in adult prison.
There are difficult days ahead, he added, but inmates such as Curtis and Catherine can overcome if they anchor themselves to a purpose and find structure. But that takes time.
"It sounds crazy, but there was a time when I felt more content when I was in prison than when I was out," Parsell said. "At least in prison I had something to look forward to. But out in the world, I had no club, no map and no guidance. I was free, but I wasn't really."
This story originally appeared on NBCNews.com