I think he wore a wire to avoid prison.
The article does imply he was caught in a drug deal and was flipped by the FBI.
However these task forces get blackmailed too. Note how Sharpton then went on TV blaspheming the police and changing the courts in the Brawley affair but the FBI could do nothing against this communist because they needed him.
Goes to show how tasks forces that do not go after fundamentals but perps only become lost in sauce of mass epidemics of crime culture while treating a single patient.