Officials say a man accused of killing nearly two dozen elderly women and who was convicted in the slayings of two has been killed by his Texas prison cellmate.

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.