Cirino participated in last week's rookie minicamp on a tryout basis. The 5-foot-11, 191-pound Cirino played two seasons at Adams State and recorded 55 tackles, three interceptions and three forced fumbles in 18 games.
He also played 11 games at Ventura College prior to attending Adams State.
Acker signed with the Colts last month after playing in 40 career games with the Kansas City Chiefs and San Francisco 49ers. The 6-foot, 195-pound Acker collected 98 tackles, four interceptions and one fumble recovery during that stretch.