A Texas prisoner accused of killing 22 older women over two years, preying on them so he could steal jewelry and other valuables, was slain Tuesday by his cellmate while serving a life sentence, prison officials said.

Billy Chemirmir, 50, who was convicted last year in the slayings of two women, was found dead in his cell at a prison in rural East Texas, Texas Department of Criminal Justice spokesperson Hannah Haney said. He was killed by his cellmate who was also serving a prison sentence for murder, according to Haney.

Chemirmir’s death comes about two weeks after Texas’ 100 prisons were placed on a rare statewide lockdown because of a rise in the number of killings inside the facilities, which prisons officials have said were related to drugs.

Haney did not release the name of the cellmate, how Chemirmir was killed or what may have led to the slaying.