A suspected serial killer and convicted murderer, who allegedly murdered nearly two dozen people throughout Dallas and Collin counties, is on trial again in Dallas County for the murder of another victim.

The latest trial of Billy Chemirmir, 49, is for his alleged killing of Mary Brooks, 87, who was found dead inside her Dallas condo in 2018. Police initially believed she died of natural causes, but an attack on another woman under similar circumstances caused them to reconsider.

Chemirmir is accused of killing 22 people, many of whom were attacked and killed in senior assisted living facilities, and is currently serving a life sentence after being convicted for the murder of Lu Thi Harris in 2018.

In that incident, the Plano police department was surveilling Chemirmir in relation to a separate offense, according to a press release. While watching Chemirmir, police observed him tossing unknown items into a dumpster.

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When he was arrested for an unrelated outstanding warrant, the suspect was found to be holding jewelry and money. Furthermore, officers found a jewelry box in the dumpster containing the name of a local resident.

Dallas police officers went to the person’s address to perform a welfare check when they found 81-year-old Lu Thi Harris dead at the scene. Other items found in Chemirmir’s possession were also identified as belonging to the victim.

A Dallas County jury convicted Chemirmir in April 2022 for the robbery and death of Lu Thi Harris, as reported by The Dallas Express. Following the conviction, he was sentenced to life in prison without the possibility of parole.

Chemirmir had been arrested after Mary Annis Bartel, 91, survived an alleged attack by the suspect in March 2018.

Bartel told police a man had forced his way into her apartment at an independent living community for seniors and took her jewelry after trying to smother her with a pillow.

Before she passed away in 2020, she described her encounter with Chemirmir in taped interviews; these were played in court at his subsequent trials. Describing the attack, Bartel said the minute she opened her door and saw a man wearing green rubber gloves, she knew she was in “grave danger.”

Collin County prosecutors have not revealed whether they will prosecute Chemirmir for the nine capital murder charges in their county against him.

Chemirmir could face a second life sentence if convicted in the ongoing case. Controversial Dallas County District Attorney John Creuzot has declined to pursue the death penalty, suggesting that Chemirmir was “going to die in the penitentiary.”