The Falcons signed safety Tyrell Johnson Sunday.

The move comes one day after projected starting free safety Dwight Lowery was placed in the NFL-mandated concussion protocol after suffering the head injury Friday night.

Johnson, 6-feet, 207 pounds, has six years of experience out of Arkansas State. He was originally selected by the Vikings in the second round (43rd overall) of the 2008 NFL Draft. He played four seasons with the Vikings. He signed with the Lions in December 2012 and played the final four games for Detroit.

In five NFL seasons, Johnson played 53 games with 23 starts and totaled 126 tackles (100 solo), two interceptions, and 10 passes defensed.

Safety Dezmen Southward, who has been out with a knee injury, returned to practice Sunday.

The Falcons also made another roster move Sunday by waiving fullback Roosevelt Nix-Jones. He was signed as a college free agent in May out of Kent State.