Katherine Cunningham was found beheaded near a bunker filled with guns on Camano Island in Washington last February.
Authorities were searching for Jacob Gonzales for Cunningham's murder when they found his DNA on the handle of a samurai sword used in the killing.
Investigators believed Gonzales had been hiding out in Merced County last summer.
In April of 2018, the Sutter County Sheriff's Office found an unidentified body in Yuba City.
They determined Tuesday the body they found was Gonzales.
The cause of his death has not yet been released.