The Bears signed Wilson on Monday to compete for the team's strong safety position. The 34-year-old Wilson, who was with the New England Patriots, missed all of last season after a preseason Achilles tendon injury. However, team officials said they were impressed with Wilson's health, athleticism and ball skills during a workout Monday.
The 6-foot-3, 230-pound Wilson is one of 13 players to have 20 or more interceptions and 20 or more sacks in their career since sacks became an official statistic in 1982.
Mastrud started 12 of 16 games for the Oakland Raiders last season. The 26-year-old caught six passes last year for 88 yards.
Wilson and Mastrud were signed to one-year contracts.