A 31-year-old man who had been under repeated questioning about the shotgun slaying of Cold Spring police officer Thomas Decker killed himself Wednesday after an hours-long standoff with law enforcement at his home near the central Minnesota city, officials said Friday.

Eric J. Thomes, described by the Bureau of Criminal Apprehension (BCA) as a "person of interest" in the Decker case, was found hanged in a metal outbuilding near his rural Cold Spring home. Thomes ran into the building when he saw investigators arrive for another interview, the BCA added.

Authorities also said that the shotgun used to kill Decker on Nov. 29, 2012, was found on property to which Thomes had access, but BCA Superintendent Wade Setter stopped short of declaring Thomes the person who killed Decker, 31, behind Winners Bar in downtown Cold Spring and urged anyone who had contact with Thomes in the past six weeks -- both before and after Decker's death -- to come forward as investigators continue to work the case.

"That would be premature for us to reach a conclusion that he is a presumptive suspect. We're trying to figure out what his role is," Setter said. "In the last 24 hours there's been a number of things that have happened. We will be able to answer that question at some point, we're just not able to make that conclusion today."

Thomes, a divorced father of two boys, had numerous run-ins with police, all involving driving and starting when he was 16 years old. He was convicted in late 2011 for drunken driving after being stopped in Cold Spring. He was then booked three times -- in September, November and December -- apparently in connection with the 2011 case, according to Stearns County jail records.

Decker assisted in the August 2011 arrest of Thomes. The arresting officer was Greg Reiter, a part-time Cold Spring officer who was with Decker the night he was killed. Reiter, who has been unable to recount many details of what happened that night, didn't leave his squad car in the seconds after Decker was shot and put his car into reverse and backed away as the shooter headed in the other direction.

About three weeks after Decker was killed, authorities released a transcript of the 911 calls. It revealed a caller reporting a black van with a noisy exhaust system leaving the area. The transcript release was accompanied by a $100,000 reward offered by authorities for information leading to the killer. Court records show Thomes drove a green Dodge van when he was ticketed Nov. 8 for driving after revocation. Setter said the BCA has recovered a vehicle similar to the one described that night. It is being examined.

Allen Lambrecht, a neighbor across the road from the property where Thomes killed himself, said Thomes drove a noisy dark green minivan. Thomes had lived on the property for at least the last nine months and was seen driving to and from the residence as often as four times a day, Lambrecht said.

He said that Thomes attended Rocori High School with his stepdaughter and was a member of the school's drum line, which competed with other schools. "He seemed like a pretty squared-away guy back then," Lambrecht said.

Thomes and Decker, both of whom grew up in Cold Spring, graduated a year apart at Rocori -- Thomes in 1999 and Decker the following year.

A man who answered the door of Thomes' parents' home midday declined to comment. "I'm sorry, we're in the midst of grieving right now," he said. When asked before the news conference about the investigation, the man said "You know as much as we do right now."

'A downward spiral'

Setter said they still refuse to rule out any suspects, including Ryan Larson, the part-time Winners bartender who was arrested in his apartment above the bar within hours of Decker's killing. The news of Thomes' death and the BCA investigation filled Larson with conflicting emotions.

On one level, Larson said Friday, he felt confused because he knew Thomes casually and viewed him "as a regular" who was always helpful whenever there was an inkling of trouble among patrons.

"He'd been on a downward spiral over the last year with arrests for DUI," Larson said in an interview. "But I don't know what was going on in his life."

Equally, Larson said he sees himself as someone whose reputation has been permanently damaged because he was arrested and held for five days before his release for lack of evidence.

Inconsistencies in story

Decker's death hit the small town particularly hard, given that the father of four grew up there and had six years on the police force. More than 3,000 people attended his funeral.

Decker's parents and his wife, Alicia, could not be reached Friday for comment.

At a news conference Friday afternoon in St. Cloud, Setter said investigators had interviewed Thomes several times about Decker's slaying based on a tip and had found "inconsistencies" in what he was telling authorities.

Shortly after 2 p.m. Wednesday, BCA agents attempted to re-interview Thomes, Setter said. Thomes fled into an outbuilding on his property southwest of Cold Spring.

BCA agents and Stearns County Sheriff's Office investigators tried for hours to contact Thomes, but he refused to come out.

Shortly before 7 p.m., agents and investigators entered the building and found that Thomes had hanged himself.

The shotgun, found at a location that authorities Friday declined to disclose, was determined by BCA laboratory firearms experts to be the weapon that "was likely" used to kill Decker.

Thomes was scheduled to appear in court Thursday for a probation violation hearing relating to the 2011 case.

According to a friend who frequently socialized with Thomes and his children, Thomes was a "wonderful person, a good father" who tried to visit with his sons every other weekend.

"I still don't think he did it -- not in a million years," said the friend, who asked to remain anonymous, of Thomes' possible involvement in Decker's killing.

"What I think happened is that he cracked under the pressure of being questioned by the police, about his DUIs, about his losing his job and being seen as a suspect. I think they pushed him over the edge. He did not do drugs. I think they were grabbing at straws."

The BCA is asking people to come forward and help investigators piece together Thomes' movements since about a week before Decker's killing until Thomes died. Anyone with information is urged to contact the Sheriff's Office at 1-877-782-5683 or the BCA at 1-877-996-6222 or bca.tips@state.mn.us.

asimons@startribune.com 612-673-4921