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Woman accused of beating cousin to death with claw hammer after night of drinking charged with murder for second time

Brianna Elise Zerth (Peoria Police Dept.) and Peter McKenna Jr. (KOLD screenshot)

Brianna Elise Zerth (Peoria Police Department) and Peter McKenna Jr. (KOLD screenshot)

A 30-year-old woman in Arizona was arrested for allegedly killing her 33-year-old cousin, who was beaten to death with a claw hammer last year. Brianna Elise Zerth was taken into custody on Friday after a Maricopa County grand jury returned a true bill indicting her on one count each of second-degree intentional murder, aggravated assault with a deadly weapon or dangerous instrument, and tampering, destroying, or altering physical evidence in the slaying of Peter McKenna Jr., court records reviewed by Law&Crime show.

Officers with the Peoria Police Department responded to an emergency call just after noon on May 5, 2022, about a dead man at a home in the area of 112th Avenue and W. Diana Avenue, the department said in a press release. First responders found McKenna — who appeared to have suffered multiple blunt-force trauma injuries — and declared him dead.

A preliminary investigation revealed that Zerth was related to the victim, who lived in the home where he was found. Zerth, who called the police, was taken into custody.

According to a report from Tucson, Arizona, CBS affiliate KOLD-TV, Zerth was initially charged following her arrest but later released when prosecutors declined to formally charge her due to a lack of evidence.

“The County Attorney’s Office received a submittal from the Peoria Police Department on Brianna Zerth for an incident on May 4. The submitted charges were second-degree murder, aggravated assault and tampering with evidence,” the County Attorney’s Office said in a statement to KOLD. “Prosecutors reviewed the evidence and referred the case back to law enforcement for additional information. Our office has had regular contact with the next of kin in this case, and we acknowledge the criminal justice system can be frustrating. We will make a decision on this case upon receiving the additional information requested.”

In court documents obtained by Phoenix, Arizona, CBS affiliate KPHO-TV, authorities said McKenna suffered multiple puncture wounds to his back inflicted with a claw hammer found at the scene. There was also blood spatter on multiple walls and the floor of the home.

Zerth reportedly told police that she and McKenna, her cousin, had been up late the previous night drinking alcohol when they began to fight. She reportedly said the specifics were “blurry,” claiming she woke up to find McKenna dead on the floor in a pool of blood. She then covered his body with a jacket, cleaned the area so her 6-year-old daughter didn’t see the body or step on broken glass, and called the police.

KOLD reported that Zerth later claimed McKenna was strangling her during the fight and caused “significant trauma,” which the medical examiner corroborated. Her self-defense claim was reportedly a problem for prosecutors, who sent the case back to police seeking “additional information.”

However, Zerth was unable to stay out of legal trouble. She was arrested in June 2022 for allegedly trying to run over her ex-boyfriend in her car. She was charged with one count each of attempt to commit aggravated assault with a deadly weapon and attempt to commit endangerment. She pleaded guilty to a lesser charge in that case and was sentenced to probation, court records show.

Zerth is scheduled to appear in court again on Wednesday for her arraignment.

The County Prosecutor’s Office and Peoria Police Department did not immediately respond to messages from Law&Crime inquiring what new information led to Zerth being arrested again for McKenna’s murder.

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Jerry Lambe is a journalist at Law&Crime. He is a graduate of Georgetown University and New York Law School and previously worked in financial securities compliance and Civil Rights employment law.