A man who Texas authorities say smothered at least two dozen elderly women in a two-year killing spree, while stealing possibly millions of dollars worth of jewelry and other valuables, was himself murdered on Tuesday morning by a prison cellmate, according to the state’s criminal justice department.

Billy Chemirmir, 50, worked as an in-home caregiver and posed as a maintenance worker to gain access to luxury independent living communities in and around Dallas. He would gain access to the apartments of seniors then force a pillow over their face, smothering them to death before raiding the apartment of its valuables to pawn or sell online.

He was convicted of capital murder once in April of last year and again in October in two separate cases in Dallas county. After securing those two convictions, Dallas prosecutors dropped additional charges against him and opted not to seek the death penalty.

Chemirmir faced another slew of charges in suburban Collin county, where prosecutors announced last month they would not seek execution.

Because he was not on death row, Chemirmir had a cellmate at the Coffield Unit prison in east Texas. That cellmate, who Texas prison authorities did not name on Tuesday, was identified as Chemirmir’s killer.

“This was jailhouse justice,” said Dan Probst, whose aunt Catherine Sinclair was the first alleged victim. “As far as Chemirmir is concerned, he is over and done with.”

Chemirmir was a Kenyan citizen and was living in the United States legally with permanent resident status. His family is from the Rift valley, between the cities of Eldoret and Nakuru. In a jailhouse interview before his convictions, Chemirmir said he grew up on his family farm and took care of his elderly father.

“I am not a killer,” Chemirmir told the Dallas Morning News in 2022. “I’m not at all what they’re saying I am. I am a very innocent person. I was not brought [up] that way. I was brought [up] in a good family. I didn’t have any problems all my life.”

He followed a sister of his to the US, where he got a job selling cars and later as a senior caregiver in north Texas. His family operates several senior living homes in the Dallas area, although no suspicious deaths have been reported there.

Chemirmir was arrested on a few drunk driving and family violence charges in 2010 and 2011, but authorities say his killing spree began in earnest in early 2016. He has been linked to at least three deaths at Edgemere, a luxury senior living community in Dallas where he was arrested for trespassing in June 2016.

Shortly after being released from jail on good behavior from that charge, authorities say he began stalking and killing women at the Tradition-Prestonwood, another senior community in Dallas. He was linked to nine deaths there between 2016 and 2018.

During all that time, most of the deaths and thefts were brushed aside as resulting from natural causes – smothering deaths leave few signs for even a trained eye. The local medical examiner testified at trial that his team missed those signs initially because police on the scene did not report any additional suspicions.

It was not until a woman survived an attack at Preston Place senior living in Plano and provided a description to police that authorities finally caught on. They set up a stakeout at his Dallas apartment and arrested him after seeing him throwing away a jewelry box from one last murder.

Chemirmir had appealed his convictions and maintained his innocence until his death. The Texas department of criminal justice said its inspector general’s office was investigating Chemirmir’s slaying.

“It wasn’t the justice that we know about through the judicial system, but … this is a form of justice,” said Shannon Dion, whose mother, Doris Gleason, died in October 2016. “My mother died in fear. This man did not have a peaceful passing. There is some relief in feeling that he didn’t get off easily.”