The three drifters accused of killing the two people are Lila Alligood, Morrison Lampley and Sean Angold.
VIDEO: Robbery may be motive in killings of strangers in San Francisco, Marin County
Steve Carter was killed while hiking in Fairfax and Audrey Carey was found murdered in Golden Gate Park last year.
It wasn't until the suspects were arrested in Portland days later and a gun was discovered in their car that the two crimes were linked.
The defendants now face the possibility of serving life without the possibility of parole.