An official says the gunman who killed nine people at an Oregon community college left a "manifesto" that was a couple pages long. The official did not reveal the contents of the document but described it as an effort to leave a message for law enforcement. The official is familiar with the investigation but was not authorized to disclose information and spoke on the condition of anonymity. The official said the document was left at the scene of Thursday's shooting but wouldn't specify how authorities obtained it. Authorities are trying to determine a motive for the mass killing.During a Saturday news conference, the sheriff said Chris Haper-Mercer killed himself as officers arrived.