American Gangster ending explained (spoilers)

[tamara]

Det. Richie Roberts (Crowe) and his men use one of Frank Lucas' (Washington) men to locate and track a load of drugs. They are lead to Newark's projects where Frank's brother Huey (Ejiofor) is supervising the cutting of the drugs. After using swift tactics to break into the apartment, a large shootout occurs and Roberts ends up chasing Huey. Frank being at church the entire time, walks out to find Roberts standing in front of the church and roadblocks on either side of the street, ready to bust him. While in custody, Frank attempts to smart-talk his way out of a large sentence, but Roberts assures him of all the charges he has against Lucas and all the witnesses willing to testify, claiming that the list stretches around the block. Left with no choice, Lucas cooperates with Roberts, giving up 75% of New York's Drug Enforcement Agency, who are claimed to be corrupt detectives. Detective Trupo (Brolin) is among the list and to avoid arrest, he shoots himself. Richie Roberts resigns from the prosecutor's office to become a defense attorney. Frank receives 70 years for conspiracy to distribute narcotics, and all his assets are seized. But his sentence is reduced to a light 15 years for his cooperation. The final shot shows Frank's release in 1991, looking older and out of place.