Who was the Inside Man? Possible spoiler

Rating: 10/10 (28 July 2007)

I believe Detective Keith Frazier (Denzel Washington) was the inside man. Why? Because Dalton Russell, bank robber (Clive Owen) planned the perfect heist. Part of his perfect planning included determining what would the hostage negotiator do ... what would he/she do next?
Denzel fell right in line throughout doing everything the bank robber planned / hoped for.
Thus, Denzel was the inside man, unknowingly. As a result of his predictability, the bank robber used him as his inside man throughout the entire robbery, to bring about the perfectly planned result.
Was Denzel a good guy? Yes, for 99% of the movie. It was in that last minute (the 1%) where he slipped over to the dark side.