The shooting death of a hunter in central Minnesota a month ago is being treated as a homicide, authorities said Wednesday, adding that they are looking for the victim’s rifle as well as the suspected killer.

“The determination of homicide as a manner of death is based on information obtained thus far in the investigation” into the killing of Terrence “Terry” Brisk, the Morrison County Sheriff’s Office said in a statement.

The Sheriff’s Office, with help from the state Bureau of Criminal Apprehension, said it has followed up on several leads and conducted several interviews as part of its investigation into who shot Brisk, of Little Falls, on Nov. 7.

Investigators believe Brisk, 41, was shot between 2:15 p.m. and 4:30 p.m. near the intersection of Hawthorne and Jewel roads in Belle Prairie Township.

As part of its investigation, the Sheriff’s Office is asking for the public’s help in locating a Winchester AE .30-30 lever-action rifle belonging to Brisk. The rifle is described as an older model, with a wooden stock and forearm, with no sling attached. Brisk was known to carry the rifle in the woods while hunting.

Brisk was an avid hunter who also enjoyed fishing, snowmobiling and camping with his family. Brisk’s survivors include his wife, Pam, and four children.

The Sheriff’s Office is looking for the victim’s rifle, which is the same type as this one.

A $20,000 reward is being offered for information leading to Brisk’s killer. Anyone with information about this case is encouraged to contact the Sheriff’s Office at 1-320-632-9233.