49ers place Asa Jackson on IR to make room for Leon Hall

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The 49ers officially announced the signing of Leon Hall to a one-year deal, which was reported earlier Tuesday. They placed cornerback Asa Jackson on injured reserve to make room.

Jackson injured his hamstring during Sunday’s game. The 49ers also had cornerbacks Ahkello Witherspoon (concussion) and Rashard Robinson (cramps) go out during the loss to the Colts.

The 49ers promoted Jackson from the practice squad on Sept. 16. He made three special teams tackles in three games.

Jackson spent four seasons in Baltimore after the Ravens made him a fifth-round choice in 2012. He played mostly on special teams, though he started six games at corner. He was in Detroit last season, starting two games.