Melvin Knox had a secret.
A dark secret he had kept tucked away for more than four decades, through stints in prison for burglary, drugs and once threatening a couple with a shotgun.
The Fort Worth Star-Telegram reports Knox's secret made his other crimes seem almost petty.
It wasn't until June 28, in a Tarrant County courtroom, that Knox — a kind-looking black man whose white hair and matching beard showed his 59 years — stood before a judge and for the first time publicly admitted his secret.
Almost 44 years earlier — as a 15-year-old boy — Knox had murdered his best friend, Donald Rodgers.
In July, Knox was sentenced to 40 years in prison — a sentence he is appealing. The 1973 murder case is thought to be among the oldest cold cases solved and successfully prosecuted in Tarrant County.
Investigating cold cases — considered to be any unsolved homicide over a year old — can be the most challenging for detectives. The older the case, the more likely that evidence is gone and that witnesses have died.
"Some of the cases have a lot of information. Some of them have zero information," said Mike McCormack, the cold case detective who reinvestigated Knox's case. "Sometimes you're starting at scratch on a case that's 30 years old."
Fort Worth police increased their emphasis on cold cases in 2002 after the department received pressure by relatives of murder victims. The department conducted a review of 760 unsolved homicides dating back to 1966, prioritizing cases based on evidence and leads.
Since then, the department has solved an estimated 128 cases. That includes cases that led to an arrest or where a now deceased suspect was identified.
"It can only be closed on the death of a suspect if, and only if, enough information is there to prosecute the individual," said detective Jeremy Rhoden, a current cold case detective.
McCormack had worked as the cold case unit's sole detective for two years before retiring from the department in 2017 and going to work for Texas Christian University police.
McCormack said he received phone calls from desperate family members every day.
"People don't call about their 1980 burglary, but they do call about the murder of their son in 1980," McCormack said. "... In that unit, it's heartbreaking. You talk to parents who are trying to get an answer before they die. Those phone calls just really tear you up."
In his two years in the unit, McCormack looked into more than 100 cold cases, seeing if there was more he could do. Maybe a new forensic test that could be performed or a new witness that he could track down.
But despite all those efforts, clearing a cold case is rare.
McCormack filed only two cases, one of them against Knox and the other involving a 2010 homicide, which is still pending.
Knox was arrested in December 2015, accused of shooting Rodgers, 14, in the face and then stabbing the teen seven times in a crime he blamed on an intruder. He was weeks away from going to trial when he decided to plead guilty to the murder charge and throw himself on the mercy of the court.
McCormack said being able to tell Rodgers' family that Knox had been arrested and had subsequently admitted to the murder was a welcome change in a unit where such calls are few and far in between.
"I really feel for the Rodgers family. My kids are about the age of Donald Rodgers now. I look at his picture and I see my kids."
"... I know that Donald Rodgers' parents passed and never got the answers. I feel it and I'm not the family. I know that tears them up. I know they feel their parents went to the grave without peace. I feel bad about that. I hope that for the family still alive, the siblings, this helps."