Youngest Children to Be Tried for 1st-Degree Murder to Be Released

A brother and sister who were convicted of killing their father's girlfriend when they were 12 and 13 years old, respectively, are set to be released in the next nine days, authorities said.

Curtis and Catherine Jones, now 29 and 30 years old, respectively, pleaded guilty to second-degree murder in the 1999 killing of Nicole Speights, according to Florida Today.

The siblings, from Cocoa Beach, Florida, were given an 18-year prison sentence, and they will be on parole for the rest of their lives once they are released, authorities said.

The two were the youngest children in U.S. history to be tried as adults for first-degree murder, according to Florida Today. They later pleaded guilty to second-degree murder.

The siblings accused a male relative of sexually abusing them, according to ABC's Orlando affiliate WFTV. But when they asked for help from their father and his girlfriend, and their pleas were ignored, they plotted to kill all three people, according to WFTV.

But after they shot Speights, they got spooked and didn't go ahead with their plan to kill the other two, according to Florida Today.

Child services found signs of abuse, but the charges were never proven, according to Florida Today.

However, prosecutors in the 18th judicial circuit told ABC News today that jealousy of the girlfriend was the main motive for the killing, and reports of sexual abuse came out in subsequent press accounts and were not dealt with in court.

Curtis was ordained as a minister while in prison and Catherine married a pen pal while she was incarcerated, according to Florida Today.

The siblings face a new world upon their release.

"Of course there are fears, mainly because there's so much I must learn to function like a normal person: how to drive, fill out job applications, text, dress for a job interview, build my credit," Catherine wrote in a letter to Florida Today in 2014.

Catherine is set to be released from Lowell Correctional Institution on Aug. 1 and Curtis is scheduled to be released from South Bay Correctional Facility on July 28, according to state records.

An attorney for Curtis Jones and an advocate for the siblings during the trial did not immediately respond to requests by ABC News for additional comment.