ST. CLOUD -- The Stearns County Sheriff's Office is officially closing the investigation into the murder of Cold Spring Police Officer Tom Decker.

Decker was conducting a welfare check near a downtown Cold Spring bar in November 2012 when he was ambushed, shot and killed.

Chief Deputy Sheriff Jon Lentz says he began reviewing the file again back in February but found no new leads.

Eric Thomes -- Stearns County Jail Photo

Police arrested Ryan Larson as a person of interest in the case but Larson was never charged.

Officers then turned their attention to 31-year-old Eric Thomes. But, Thomes committed suicide in 2013 as police were closing in to conduct a second interview with him.

Eric Thomes was (I'll characterize it as) the main focus of the investigation at that time.  And, reviewing the case and speaking to investigators involved, they're confident, and I'm confident in their assessment as the sheriff is...that had he not committed suicide and had we had the ability to bring him in for an interview that they would have been able to confirm certain aspects of this case.

A shotgun linked to the murder was also found on the family property where Thomes was when he died.  Lentz says the investigative trail ended after the suicide and the discovery of the gun used in the killing of Officer Decker.

Coming up on five years since Eric Thomes' suicide.  The evaluation really is that there really hasn't been anything substantial added to that case or the investigation.  It's time to close the file.  Certainly, if something new were to come to light, there was new information or somebody came forward we'd reopen the investigation, take a look at the information and proceed from that point.

Lentz wouldn't comment on Larson because there are civil lawsuits pending brought by Larson against law enforcement, media outlets and others.

Once the case file is redacted to hide sensitive information, Lentz says it will be made public.