New York ? An inmate in prison for killing his landlady drew an extra 15 years Thursday for another slaying that was wrongfully pinned on a mentally disabled man.

“I’m aware that I will spend the rest of my life in prison,” said Eldred Johnson Jr., who was already serving 25 years to life. “Before I go, I just want to apologize. … Because of my action, I put this court in a position to create an injustice.”

Douglas Warney, 45, who has an IQ of 68, spent more than a decade behind bars after confessing to the stabbing death of community activist William Beason in 1996. He was released last year after DNA tests, which prosecutors initially tried to block, tied Johnson to the killing.

Johnson, 42, pleaded guilty in March to second-degree murder, claiming he was angered when the 63-year-old Beason repeatedly solicited him to have sex. Evidence collected at Beason’s apartment eventually led authorities to Johnson through a DNA database of convicted felons.

Johnson slashed his landlady’s throat in Utica in late 1995 and fled to Rochester, where he killed Beason two weeks later. He pleaded guilty to the Utica murder in 1998.