MINNEAPOLIS (WCCO) — With stern looks and steely determination, authorities came into a Bureau of Criminal Apprehension news conference dangling a big carrot.

It’s a reward of up to $100,000 for the tip that leads to the person who gunned down Cold Spring police officer Tom Decker on November 29 2012.

“We want someone to come forward with any piece of information they have, no matter how menial it may seem to them,” said BCA superintendent, Wade Setter.

The reward money is coming from private donations through Spotlight on Crime, a partnership between Minnesota businesses and public safety officials.

In addition, the reward will be advertised using several electronic and conventional billboards. Two will be seen along Division Street in St. Cloud and another near downtown Cold Spring.

While authorities search for new leads, dive teams were back on the scene of the nearby Sauk River, just a block east of where officer Decker was gunned down. They are searching once again for the 20-gauge shotgun believed used in the murder. Authorities have reason to believe it may have been thrown into the water in an attempt to dispose of the murder weapon.

BCA investigators are also asking the public’s help locating a black mini-van that was seen leaving the crime scene just a short time after the killing. They say that van has a very loud muffler as described by witnesses.

Stearns County Sheriff, John Sanner added, “This is a cold blooded killing. And the sooner we get this individual responsible for this behind bars, the better all of us will sleep at night.”

Investigators also confirmed the other officer on duty that night, and responding to the call for a welfare check of Ryan Larson is 38-year-old part-time officer, Greg Reiter.

According to court documents detailing his early statements to investigators, he did not get out of his squad after seeing officer Decker gunned down in the parking lot behind Winner’s Bar.

He was also unable or chose not to return fire with the man he observed standing over Decker’s body and then walking away. That statement is troubling to investigators who say it is unusual for an officer to react that way when a killer has gunned someone down.

Reiter remains on paid administrative leave, which is mandatory in a case such as this and is cooperating with the investigation.

“The specifics are part of an ongoing investigation. But I would expect that both officers would be getting out of a squad on a call though,” said Assistant BCA Superintendent, Drew Evans.

Anyone with information on the case is asked to contact the Stearns County Sheriff at 1-877-782-5683 or the Minnesota Bureau of Apprehension at 1-877-996-6222. Reward tips can also be emailed to the BCA at bca.tips@state.mn.us.

Evans adds that informants are treated confidentially and can remain anonymous.