Billy Chemirmir Trial: Prosecutors present DNA evidence against accused serial killer

Prosecutors brought DNA evidence against accused serial killer Billy Chemirmir for one of the 22 murders he's charged with on Wednesday. 

This case is over the 2018 death of 87-year-old Mary Brooks, but Wednesday prosecutors presented the evidence to a different victim.

Martha Williams was found dead in her apartment at a Collin County retirement center in March 2018.

Prosecutors say his DNA was found on her fingernails, on a pillow they believe he used to smother her and on gloves recovered from his car.

Prosecutors hope the DNA evidence convinced jurors Chemirmir killed before, and had a specific, repeated method.

Dallas County Chief Medical Examiner Dr. Jeffery Barnard explained how smothering would have worked quickly.

"At some period of time it would take, I would imagine, no more than a few minutes at the most where the heart rate drops after they're not breathing, they're unconscious and then eventually they die," he said.

The defense did not cross-examine Dr. Barnard and only asked a few questions to the other witnesses called to testify.

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Prosecutors have turned to other victims to show the jury a pattern of attacks allegedly done by Chemirmir.

Chemirmir has already been convicted of murder in the death of Lu Harris.

The majority of Chemirmir’s alleged murders happened at senior living facilities, where prosecutors say he posed as a maintenance worker. 

Prosecutors are looking for a second life sentence for Chemirmir, making it less likely his sentence is thrown out on appeal.