The Chicago Bears signed safety Troy Nolan on Wednesday to add depth in a depleted area. Nolan has five tackles in seven games this season for Houston and Miami. He started one game for the Texans after returning to Houston from the Dolphins earlier in the season. Bears starting safety Chris Conte is battling a hamstring injury and his availability is uncertain for Sunday's game against Detroit. The Bears also are without veteran safety Craig Steltz, who was placed on injured reserve earlier this season, leaving them with Anthony Walters as the only other safety on the roster. A seventh-round draft pick by the Texans in 2009, Nolan has 73 tackles, three interceptions, nine passes defensed, 1.5 sacks and a fumble recovery in 37 games over four seasons.