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Crime & Safety

Spurned Suitor Sparks Double Homicide

A recent break-up led to an early morning shoot out on Liberty Road that left an off-duty Marin County Sheriffs deputy and the spurned suitor dead.

The early Tuesday morning that left a Marin County Sheriff's Deputy and the spurned boyfriend dead was caused by a rocky relationship that had recently ended, according to the Sonoma County Sheriff's Office.

The victims have been identified as Jim Mathiesen, 49, a Marin County Sheriff's Deputy, and Thomas Edwin Halloran, 28, who had been dating Mathiesen's friend. 

“They had been dating off and on from March until May," said Lt. Lorenzo Duenas, a spokesman for the Sonoma County Sheriff's Office. "Nine days ago they break it off and he starts texting and calling and making death threats."

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Police reports describe the tragic events commencing when the young woman asked Mathiesen, a family friend, for help because Halloran had made death threats to the girl and her family.

Mathiesen arrived at the Liberty Road residence between 11:30 and 11:50 p.m. Monday night. Approximately 20 minutes later Halloran arrived. When Mathiesen walked outside to ask Halloran to leave the property Halloran shot the unarmed Mathiesen twice in the upper body, killing him.

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“The girl takes off, running on foot, and Halloran grabs another female in the residence and puts a gun to her head and starts dragging her towards a vehicle,” Duenas said.

Halloran then threatened to shoot the hostage if she didn’t help him find his ex-girlfriend.

While Halloran attempted to flee with the hostage, a third resident of the home grabbed a firearm and shot Halloran twice, once in the upper body and once in the lower body, killing him. The hostage was unharmed.

“All parties were found and interviewed. At this point the shooting of Halloran looks like justifiable homicide,” said Duenas.

When the dust cleared, it was determined that Halloran was on active state parole for making terrorist threats in the past and had numerous arrests in both Marin and Sonoma Counties.

Due to Halloran’s possible gang and/or prison affiliations, the name of the person who shot him are not being released or confirmed by the Sheriff’s Department. Because the young woman who was dating Halloran is a victim of domestic violence, the Sheriff's Office has asked that her name remain confidential. 

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