Wyoming

Wyoming police probe letter written by senior center shooter

  • A man killed by a shooter at a senior citizen apartment is covered by a sheet on a stretcher Wednesday, Sept. 14, 2016 in Cheyenne, Wyo. A 77-year-old man living at the senior citizen apartment complex shot three people at the complex, killing one of them, and then killed himself nearby as officers closed in on him. (AP Photo/Mead Gruver)

    A man killed by a shooter at a senior citizen apartment is covered by a sheet on a stretcher Wednesday, Sept. 14, 2016 in Cheyenne, Wyo. A 77-year-old man living at the senior citizen apartment complex shot three people at the complex, killing one of them, and then killed himself nearby as officers closed in on him. (AP Photo/Mead Gruver)  (The Associated Press)

  • A Cheyenne Police officer guards an entrance to  Heritage Court Apartments Wednesday, Sept. 14, 2016 in northeast Cheyenne, Wyo.  A 77-year-old man living at a senior citizen apartment complex shot three people at the complex Wednesday, killing one of them, and then killed himself nearby as officers closed in on him, police said. (Blaine McCartney/The Wyoming Tribune Eagle via AP)

    A Cheyenne Police officer guards an entrance to Heritage Court Apartments Wednesday, Sept. 14, 2016 in northeast Cheyenne, Wyo. A 77-year-old man living at a senior citizen apartment complex shot three people at the complex Wednesday, killing one of them, and then killed himself nearby as officers closed in on him, police said. (Blaine McCartney/The Wyoming Tribune Eagle via AP)  (The Associated Press)

  • Police gather evidence at the scene where a man shot three people and killed himself at a senior citizen apartment in Cheyenne, Wyo., Wednesday, Sept. 14, 2016. A 77-year-old man living at the senior citizen apartment complex shot three people at the complex, killing one of them, and then killed himself nearby as officers closed in on him. (AP Photo/Mead Gruver)

    Police gather evidence at the scene where a man shot three people and killed himself at a senior citizen apartment in Cheyenne, Wyo., Wednesday, Sept. 14, 2016. A 77-year-old man living at the senior citizen apartment complex shot three people at the complex, killing one of them, and then killed himself nearby as officers closed in on him. (AP Photo/Mead Gruver)  (The Associated Press)

Police in Wyoming say they are investigating a letter written by a 77-year-old man who shot three people at the senior citizen apartment complex where he lived before killing himself.

Cheyenne Police Department spokesman Dan Long did not comment Thursday on what the letter said.

Larry Rosenberg gave the letter to complex resident Mary Eastman before he opened fire.

Eastman says Rosenberg expressed frustration in the letter about poker parties being held in a common area of the complex.

Long says police believe there may have been what he called "longstanding animosity" between Rosenberg and the victims.

A complex employee was killed and two residents were wounded in the shootings Wednesday. They have not been identified.

Police say Rosenberg shot himself with a handgun as they approached him.