Terms were not disclosed, but the Seattle Post-Intelligencer reported it is a five-year deal worth an estimated $9.4 million.
Selected 11th overall, Trufant had three interceptions and 69 tackles last season for the Cougars. He also returned 32 punts for 341 yards and is at his best in man-to-man coverage.
Trufant was the second cornerback taken in the draft behind Terence Newman, who was selected fifth overall by the Dallas Cowboys. He missed five games for Washington State in 2001 due to a fractured hand but returned with a cast on the hand and had three interceptions.
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