The writer apologized for the "hurt and pain" caused to the family of Larry Bradley, the Columbus Dispatch reported.
Gallia County Sheriff Joe Browning told the newspaper Tuesday he got the handwritten letter around Christmas and debated for days whether to release it to the public. He said he is still unsure if the letter was written by Bradley's killer and whether, if it is genuine, publishing it would convince the writer to come forward.
Bradley, 45, of Bidwell, Ohio, was shot at about 8:30 a.m. on Dec. 2, the opening day of the firearms deer season. He called his wife, Denise, telling her he needed help, although he did not give the details of what happened.
Emergency workers found him dead 18 feet above the ground in his stand.
"I am so sorry for the hurt and pain that I caused on that day can u please tell the family I am so sorry," the letter sent to Browning's office said.
Browning said he eventually decided to release part of the letter. He told ABC News it is likely the shooting was accidental.
"I think it's probably something that is really bothering the shooter, and it's not something that they are dealing with easily," he told the Dispatch.
Bradley, a native of Gallia County, a rural area on the Ohio River in southeastern Ohio, leaves a young son and daughter. He served in the Marines and later in the Naval Reserve in the Gulf War of 1990 and the 2003 invasion of Iraq.