FBI agents say they apprehended Enrico M. Ponzo on Monday night in the small Idaho town of Marsing, where he was living under the assumed name Jeffrey John Shaw.
Ponzo, who once lived in Boston, was charged in 1997 along with 14 others in a 40-count federal indictment that included racketeering, attempted murder and conspiracy to murder.
Federal prosecutors accuse Ponzo specifically with the 1989 attempted murder of Frank Salemme. Known as "Cadillac Frank," Salemme is the former head of the New England mob.
Ponzo is also charged with a series of other crimes in efforts to kill those loyal to Salemme.