Tyler Hilinski, a Washington State quarterback who played in eight games for the Cougars last season, was found dead in an apartment on Tuesday with what the authorities said was apparently a self-inflicted gunshot wound to the head.

The police in Pullman, Wash., where the university is, said that officers had responded to the apartment complex around 4:30 p.m. to check on Mr. Hilinski after he did not show up for practice earlier Tuesday.

They found Mr. Hilinski, 21, dead in the apartment, and they recovered a rifle and a suicide note. The authorities did not reveal the contents of the note.

In a statement, they said detectives were working with the Whitman County Coroner’s Office to conduct an investigation and confirm what they called “the suspected cause and manner of death.”