Complex sentence: In 2009 the F.B.I. believed that Coppola was going to turn state's evidence against the Genovese family and cooperate with the F.B.I. The F.B.I. was willing to give him immunity from prosecution and enter him in the Witness Protection Program if he cooperated.
Split into simpler sentences: In 2009 the FBI believed that Coppola was going to turn state's evidence against the Genovese family and cooperate with the FBI. The FBI was willing to give him immunity from prosecution and enter him in the Witness Protection Program if he cooperated.