Marin County Deputy Shot in Double Homicide

Jim Mathiesen, 49, a nine-year veteran of the Marin County Sheriff's Office was shot in the chest just after midnight in Petaluma.

Mathiesen, a Petaluma resident, was attempting to help a family friend, who had been in a tumultuous relationship with Thomas Halloran, 28.

Investigators believe Mathiesen arrived at the woman's home after she received a death threat from Halloran late Monday night. There was then a fatal confrontation between Halloran and Mathiesen, who was unarmed.

According to :

The fatal confrontation occurred when Mathiesen went outside the house to try to calm Halloran down, [Assistant Sonoma County Sheriff Lorenzo] Duenas said.

Halloran shot Mathiesen twice in the upper torso, and Halloran's ex-girlfriend fled, Duenas said.

Halloran then allegedly took another woman who was living in the house hostage and forced her into a car, Duenas said.

Another male who was living in the house then shot Halloran in the leg and upper torso in defense of the female hostage, Duenas said.

Mathiesen and Halloran were both pronounced dead at the scene.

Mathiesen is survived by his wife and two children. Read the rest of the story on .