HERKIMER, N.Y. (WKTV) - Authorities say that a Proctor High School math teacher died of a self inflicted gunshot wound at an Old Forge motel in August.

Catherine Koestner, 30, was shot and killed on August 25 in a room at the Forge Motel that she was sharing with her boyfriend, but her death remained a mystery for more than a month as authorities tried to piece together what had happened.

Koestner was shot around 1 a.m. and a motel employee told authorities they heard people arguing shortly beforehand. Some of Koestner's belongings were found scattered in the roadway several hundred feet from where she died. She was pronounced dead just before 9 a.m. Acting Herkimer County District Attorney Jeffrey Carpenter says Koestner had been drinking and was likely legally intoxicated.

Authorities said that while Koestner was predominantly left-handed, she was shot on the right side of her head.

"She was left-handed and the injury, as I stated, was to the right side of the head. However, through the investigation we did determine that she was capable of using her right hand and, in fact, did things that required some fine motor skills with her right hand, so she was predominantly left handed is how it was characterized to us," Carpenter said.

At the scene, police took into custody a legally-possessed weapon, which they revealed Tuesday to have belonged to Koestner's boyfriend, Joe Moore.

Following Koestner's death, officials interviewed Moore, and said he was being treated as a witness. Authorities said Tuesday that a few days into the investigation, Moore hired an attorney and stopped cooperating with investigators.

"We would like to get all the answers for the family and for the friends of Miss Koestner, but without the cooperation of Mr. Moore, there are a few aspects of this investigation that we're not completely comfortable with," says NYS Police Captain Mark Lincoln.

D. A. Carpenter says Koestner's death certificate will be changed from "pending further investigation" to "undetermined" and that the investigation remains ongoing.