The Chicago Bears defense has long been the source of the team's identity, and the nucleus of last year's solid unit will be back in 2012. But the Bears will have two key defensive line contributors in Israel Idonije and Amobi Okoye that can test the open market this off season if they so choose, and if they don't bring either back, new GM Phil Emery will have to find some replacements to reinforce the depth of the line. According to Michael C. Wright of ESPN Chicago, the Bears are most likely to bring back Okoye, who was on a cheap one-year contract last season and should be able to be signed for a cap friendly number. Idonije meanwhile will likely be allowed to see what he can command in the open market, as the Bears are unlikely to give him a sizable contract with the team already paying a ransom to fellow defensive end Julius Peppers. Wright suggests that if the Bears look to upgrade their defensive line this offseason, they should look at the draft, which is deep this year at defensive end and defensive tackle, especially compared to a free agent class that is considered mediocre after Pro Bowl DE Mario Williams, who is considered to be much too pricey for Chicago. Stay tuned to SB Nation Chicago for more information, and for in-depth analysis on the Chicago Bears be sure to visit Windy City Gridiron. Visit SB Nation NFL for more news and notes around the league.