An off-duty Marin County sheriff's deputy and a parolee from Novato were killed early Tuesday during a gun battle in Petaluma, authorities said.
Deputy Jim Mathiesen, a 49-year-old Petaluma resident, was shot twice in the upper body and pronounced dead at the scene, according to the Sonoma County Sheriff's Office. Mathiesen was unarmed.
The suspected killer, Thomas Edwin Halloran, was then shot to death by someone else at the rural residence. Halloran, 28, had a long criminal record in Marin and Sonoma counties for drug offenses, criminal threats and other violations.
Mathiesen, who was killed while trying to protect Halloran's ex-girlfriend from the suspect, is survived by a wife and two children, authorities said.
"This is tragic news," Marin County Sheriff Bob Doyle said. "Jim died trying to help others. He was known for his kindness and his helpful nature."
Mathiesen was shot to death around 12:15 a.m. in the 800 block of Liberty Road, where Halloran's ex-girlfriend lives, said Sonoma County sheriff's Sgt. Carlos Basurto.
The relationship between Halloran and the woman had recently ended, and the woman asked Mathiesen, a family friend, to come over to provide advice and assistance about death threats coming from Halloran, Basurto said. Halloran had threatened the woman and her family on Monday evening.
About 20 minutes after Mathiesen arrived, Halloran showed up at the property. When Mathiesen went outside and asked Halloran to leave, the suspect pulled out a handgun and shot the deputy twice in the upper body, Basurto said.
Halloran then held another resident at gunpoint and threatened to shoot her if he did not locate his ex-girlfriend. While Halloran was trying to force the hostage into a vehicle, another resident of the house grabbed a gun and shot Halloran twice to defend the hostage.
Halloran died at the scene. Neither the hostage nor the other occupants were injured, and investigators recovered all the weapons.
The names of the other victims were withheld because of Halloran's "possible gang and/or prison affiliations," Basurto said.
Halloran, who was on active state parole, has a history of arrests in both counties, and was once identified in court documents as a confidential drug informant for the Marin County Major Crimes Task Force.
In July 2008, while wanted on suspicion of threatening and stalking a girlfriend in Petaluma, he was arrested after a large manhunt and helicopter search off Atherton Avenue in Novato.
Mathiesen had been a sheriff's deputy for nine years, primarily working in the county jail and the court.
"I was always taken by him simply because he entered law enforcement later, and there was a certain maturity to him, and he was almost like a father figure," Doyle said.
Contact Gary Klien via email at firstname.lastname@example.org