Marshall signed with the Raiders on Tuesday, Adam Schefter of ESPN reports.
Marshall was let go by the Raiders before the season began, but the team brought him back to possibly have an immediate role on defense. Vontaze Burfict has been suspended for the rest of the year, so the team's only middle linebacker is Dakota Allen, who hasn't actually been deployed on defense yet. Marshall is just two years removed from his third 100-tackle season, so he's in line to start as soon as Sunday's game against the Lions.