The document refers bitterly to having a lonely existence with little actual human connections besides his online communications.
The official who released this information was not authorized to do so and said that authorities were reviewing the complete document that he described as someone rambling.
Investigators believe the shooter appeared to be associated with an online loosely affiliated community known only as beta boys that tended to glorify other mass shootings that were similar to the attack in Oregon.
The document he left behind, and one it is believed that he wrote, lamented having a life that was isolated with little promise, said the official.
Authorities thus far have released little detail about the shooter Chris Harper Mercer. Federal authorities identified him as the shooter at Umpqua Community College.
The online activity of the suspect and the statements from his neighbors and family offer a portrait of a young man, who showed at time profound loneliness and hostility towards organized religion.
According to a number of accounts from family members and witnesses of those who were wounded, the gunman asked his victims to state what their religion was prior to opening fire.
Officials in law enforcement said that the gunman had four weapons in his possession – one rifle and three handguns.
One weapon was registered to another person, according to officials.
The official also said that officials were working to trace further the path of that weapon and how it was in the hands of the gunman.
Two more weapons, also handguns, were located near the shooting scene and law enforcement was trying to determine if those too were associated with the shooter.
More weapons were also found at the gunman’s home where he had lived with his mother.
Police killed Mercer during a firefight with law enforcement officials who had rushed onto the college campus after 91 calls had been made about the shooting.