"Mike Martz resigned from his position as Chicago Bears offensive coordinator on Tuesday, according to a league source.

The source said Martz walked into Bears coach Lovie Smith's office Tuesday morning and announced that he did not intend to return to the team because of philosophical differences over how the Bears would run their offense.

There had been rampant speculation as the season dragged on that Martz could be done in Chicago. Smith was noncommittal when asked Monday during his end-of-year news conference if Martz will return next season."