It started as a night of drinking between cousins. It ended with one of them dead on the floor — and the other reaching for a vacuum cleaner.
Brianna Zerth, 33, of Peoria, Arizona, has been sentenced to 21 years in prison after admitting she beat her cousin, Peter McKenna Jr., 33, to death with a claw hammer on the night of May 4, 2022. The case, already disturbing on its face, took an even darker turn when investigators learned what Zerth did after the killing.
According to police, Zerth and McKenna had been drinking together late into the night at his home near 112th Avenue and West Diana Avenue when a fight broke out. When officers arrived the following afternoon — responding to an emergency call just after noon on May 5 — they found McKenna with multiple blunt-force trauma injuries. He was already stiff and cold.
Zerth told investigators her memory of the night was “blurry.” She claimed she woke up to find her cousin already dead in a pool of blood. But what happened next stunned investigators.
Rather than calling 911 immediately, Zerth covered McKenna’s body with a jacket — and then tried to vacuum up his blood from the floor. She also picked up broken glass from the scene, saying she didn’t want her daughter to step on it.
Only after her cleanup attempt did she finally call police — telling them her cousin was “stiff and cold to the touch.”
Zerth later claimed McKenna had been strangling her during the altercation, causing her significant injury — a claim that a medical examination reportedly corroborated. That self-defense angle likely influenced prosecutors’ early decision to release her after her initial arrest, citing a lack of evidence to formally charge her.
She was eventually re-indicted on second-degree murder, aggravated assault, and evidence tampering. In April, she accepted a plea deal — pleading guilty to one count of domestic violence manslaughter in exchange for prosecutors dropping the more serious charges.
On sentencing day, the judge handed down the maximum penalty allowed under the plea: 21 years. Zerth was credited with just under three years already served — roughly 1,056 days — meaning she has approximately 18 years left to serve.
What This Means: The case is now closed on Zerth’s end, but it raises uncomfortable questions about how long it took the system to get here. She was arrested, released, then re-indicted — nearly three years passed before she faced a courtroom. For McKenna’s family, justice came — but it came slowly.
Peter McKenna Jr. was 33 years old. He was killed in his own home, by someone he trusted enough to spend the night with. No vacuum cleaner, no jacket, no blurry memory could change that.
