A Queens ex-con whose murder conviction was tossed out by prosecutors is back behind bars — this time charged with gunning down a 19-year-old man.

Shamel Capers was found guilty in 2016 of killing 15-year-old D’aja Robinson with a stray bullet while she rode a Q6 bus in Jamaica after a Sweet 16 birthday party.

Capers was sentenced to 15 years to life in prison for his role in the senseless slaying.

But the convicted killer was set free in 2022 by the Queens District Attorney’s office, after a witness in the case was caught admitting he lied about the case in a phone call to his mother.

In a statement at the time, Queens DA Melinda Katz called the earlier conviction a miscarriage of justice.

Shamel, who served eight years in prison before his release, is now charged in another shooting death, with the victim found on July 23 in the drivers seat of a car on Rockaway Parkway with a gunshot would to his chest, police sources said.

The Queens DA’s office did not immediately respond to a request for comment.