COLD SPRING, MINN. - Ryan Michael Larson is studying to become a machinist, taking second-year milling classes at a community college in St. Cloud. He visited his grandmother on Thanksgiving. He's an avid shooter of firearms, like a lot of people around this central-Minnesota town of 4,000.

And Larson amazes folks with his ability to ace history and geography questions on the video trivia games at Winners, the corner saloon just down some wooden steps from his apartment above the back end of the bar.

When police officer Thomas Decker was shot in the face behind the adjacent bowling alley within 100 yards of those steps on Nov. 29, Larson, 34, was instantly thrust into the public glare as the prime suspect in the brutal slaying -- the reportedly suicidal man Decker was sent to check on. A week ago, Larson was locked in the Stearns County jail, his mug shot displayed everywhere.

But five days after the shooting, despite a judge giving prosecutors an extra 24 hours to prepare a case again Larson, he was released. Bureau of Criminal Apprehension officials have said he remains a suspect, but the Stearns County attorney said the amount of evidence "wasn't even close" to being sufficient to hold him any longer.

Larson apparently has been spending time with family members since he left jail. Relatives had called police the night of the shooting, worried about texts from Larson that he wanted to end his life, texts that Larson told the St. Cloud Times were misinterpreted.

Investigators recently have been questioning people in connection with drug raids in Minneapolis, a sign of a wider-ranging manhunt and a hint they might be less concerned that Larson shot Decker.

Police have cautioned him to stay out of Cold Spring for his safety, offering to have officers escort him when and if he needs to come back for belongings. Larson's mother declined to be interviewed, and Larson didn't respond to messages left with her or with friends and other relatives.

He insisted he was innocent in a jailhouse interview with the St. Cloud Times, saying he was asleep and only realized his life was going to be turned upside down when officers barged through the door for his midnight arrest about an hour after Decker was killed. Larson has since called a couple of television reporters, restating his innocence and sharing kind words about Decker, whom he knew casually.

He once bought drinks for Decker and his wife, Alicia, after the officer helped break up a barroom scuffle at Winners. Larson has filled in as a bartender at Winners' second location in Sartell.

"He's a smart guy who really likes to learn," said LaRae Scoles, who owns Winners with her husband and son, both named Jeff.

The Scoleses paint a picture of Larson as a stern barkeep who never lets patrons drink after closing. The younger Jeff, who took conceal-and-carry firearm classes with Larson, says his friend has a permit and regularly carries a .40-caliber semi-automatic pistol and also owns an AR-15 rifle like the ones Navy SEALs use.

Friends say Larson has a brother who serves in the military and is stationed in North Carolina.

"He liked guns, but he's very cautious with them," Jeff Jr. said. "He's not the type who would go out there like a monster. He was normal."

The young Scoles and Larson grew up together in St. Joseph, where Larson's family lived in a lakeside housing development called Pleasant Acres, just north of town.

"He was a nice kid," said Dale Schneider, whose son played football with Larson at North Middle School.

Along with his brother, Larson has a sister who lives in Minnesota. His parents are divorced, with his mother remarrying and his dad living in Wisconsin. Public records show Larson has lived at several addresses in the St. Cloud area during the past decade.

The Scoleses said Larson has been frustrated at school lately because there weren't enough machines for him to complete his milling work. He also had a nasty break-up with a girlfriend a year or so ago.

According to a 2009 affidavit filed by a 35-year-old former girlfriend, Larson had temper issues. She told authorities he could become "instantly very angry, aggressive and agitated" -- often breaking her belongings "in a fit of rage."

"With each incident, the violence level goes up," the woman stated in court documents in Stearns County. "It's starting to escalate and snowball, and I am fearful. ... He deals with unfavorable situations with violence, anger and aggression. And knowing that Ryan has a gun in the house with ammo only makes me more scared."

Minneapolis defense attorney Joe Friedberg, who shared a phone call with Larson's mother before his release, says the gaps in the case against Larson lead him to believe "this guy might be innocent."

Friedberg said he assumes tests of Larson's skin and clothing for gunpowder residue must have come back negative or Larson would have been charged. He said handgun residue tests are more accurate than those from a shotgun, which authorities are searching for as the murder weapon.

"But certainly a shotgun does leave residue," Friedberg said. "It's beginning to sound like it couldn't possibly have been Larson."

Heidi Everett, director of Institutional Advancement at St. Cloud Technical and Community College, confirmed Larson was a second-year student in the school's machine-tool program. Like everyone in the area, she's hoping the investigation gets resolved soon.

"We are hoping for a swift and accurate and appropriate solution to the case," she said.

curt.brown@startribune.com • 612-673-4767 larry.oakes@startribune.com • 612-673-1751