Ryan Michael Larson, of Cold Spring, was held Friday on suspicion of second-degree murder. The county attorney's office was considering criminal charges.
A six-year police veteran described as a "hometown boy" was shot to death late Thursday in what authorities called an ambush killing.
Officer Tom Decker was responding to a report of a suicidal man when he was shot twice after getting out of his squad car near an apartment behind a downtown bar. He died at the scene.
Ryan Michael Larson, 34, of Cold Spring, was held Friday on suspicion of second-degree murder. The county attorney's office was considering criminal charges.
Stearns County Sheriff John Sanner said his department got a call about 9 p.m. from Larson's family members that he might be suicidal. Cold Spring police went to his home once and couldn't raise anyone, then returned almost two hours later.
It was on the second trip that Decker was shot. He was wearing a bulletproof vest.
"It's apparent to us the officer was ambushed at the scene," Drew Evans, assistant superintendent of the state Bureau of Criminal Apprehension, said.
Cold Springs Police Chief Phil Jones described Decker as a "chief's dream." Jones said Decker grew up on a farm south of town, and after graduating from college, worked at several small Minnesota police departments before coming home for what he called his dream job.
"He was a hometown boy," Jones said.
He described Decker as the "department jokester" on a force with only eight full-time officers. Decker served as the department's instructor on firearms and use of force.
"Not only did I have no problems with him, but he was the type of officer who accumulated six letters of appreciation and commendation in six years with us," Jones said. "We lost an officer, the community lost a citizen."
Decker leaves behind a wife and four young children, the chief said.
Though a suspect was in custody, police with dogs searched downtown Cold Spring, which is about 20 miles southwest of St. Cloud, on Friday.
Larson had drawn police attention before in the community of about 4,000, mostly for traffic-related offenses but once in an abuse case.
In 2009, he reached a plea agreement to settle a misdemeanor disorderly conduct charge for engaging in behavior that could "arouse alarm, anger, or resentment in others." As part of the plea deal, he served a day in jail and had another three months stayed, but he agreed to undergo domestic abuse counseling. A no-contact order was issued. Court files indicated he violated his probation in 2010.
Civil court records show Larson was sued more than once over outstanding debt and was evicted from a rental property in 2008 for failing to pay his rent.
Condolences came from fellow police officers in other Minnesota departments and from elected officials, including Gov. Mark Dayton.
"Cold Springs Police Officer Tom Decker was senselessly murdered last night, while acting in the line of duty," the governor said. "On behalf of the people of Minnesota, I extend my deepest sympathies to his family and to the Cold Springs Police Department for their tragic loss of an outstanding officer, father and friend. Officer Decker died, while protecting his fellow citizens. For his heroism, we will be forever grateful."