COLD SPRING -- On this last day of 2012, we bring you the number one WJON news story of 2012...the murder of Cold Spring Police Officer Tom Decker. 

It was about 11:00 p.m. Thursday, November 29th when Cold Spring Police Officer Tom Decker and a partner were conducting a welfare check on a possible suicidal man. An unsuspecting Decker was ambushed and shot in the head behind Winner's Bar.

Officers from the Stearns County SWAT team and the Minnesota Bureau of Criminal Apprehension descended on the scene and arrested Ryan Larson. The 34-year-old St. Cloud Tech College student and bartender lived above the bar and was the subject of the welfare check. But, Larson said he was sleeping at the time and had nothing to do with the shooting. He was released days later without being charged.

To this day, authorities haven't found the gun used in the shooting.

Police documents later revealed Decker's partner, Greg Reiter retreated from the shooting and didn't pursue the gun-wielding assailant as he walked away. The documents outline the chronology of the night and helps shed light on why no one is in custody.

Cold Spring Police Officer Tom Decker

Police Chief Phil Jones called Officer Decker a "chief's dream." One of just nine officers in the department - Jones says Decker had received six letters of appreciation and commendation during his six-and-a-half-years on the force.

Decker left behind a wife and four small children from a previous marriage.

Decker"s funeral brought approximately 3,200 people to pay their respects, including more than 2,000 police officers from all over the midwest.

Police continue to ask for leads in the case and continue searching for the gun used in killing police officer Tom Decker. A $100,000 reward is being offered for information in helping solve the case.