McKINNEY, Texas (AP) — A Texas prosecutor says he will not seek the death penalty for a man convicted of killing two elderly women and suspected of killing nearly two dozen total.

“Billy Chemirmir is an evil person who preyed upon our most vulnerable citizens,” Collin County District Attorney Greg Willis said in a statement Thursday.

“Although he is certainly deserving of a death sentence, my decision ... is informed by the fact that he has already been tried three times in another county and he will never be a free man again,” Willis said.

The first murder trial of Chemirmir, 50, for the slaying of Lu Thi Harris, 81, ended in mistrial in Dallas County. He was later convicted in a second trial for Harris’ death and convicted of a second killing in the death of Mary Sue Brooks, 87.

Chemirmir has maintained his innocence of the crimes.

Authorities say Chemirmir preyed on older women, killing them and stealing their valuables.

He was caught after a 91-year-old woman survived an attack and told police he forced his way into her apartment at an independent living community for seniors, tried to smother her with a pillow and took her jewelry.

Police said they found Chemirmir the next day in the parking lot of his apartment complex holding jewelry and cash, having just thrown away a large red jewelry box. Documents in the jewelry box led them to the home of Harris, who was found dead in her bedroom.