Federal authorities have expanded the racketeering charges against Paul Bergrin, the North Jersey lawyer accused of turning his law practice into a criminal enterprise.

Additional drug trafficking, witness tampering and conspiracy charges have been added to a case that already includes allegations of murder, attempted murder and cocaine distribution.

Bergrin, arrested last year, is being held without bail.

Three of his codefendants, including his longtime girlfriend, his former law partner and an alleged drug kingpin, have pleaded guilty and are cooperating. The expanded charges are believed to be based in part on information they have supplied to investigators.

Bergrin, 55, of Nutley, N.J., and Alejandro Barraza-Castro, 34, of Newark, an accused drug dealer, were charged in a superseding indictment, U.S. Attorney for New Jersey Paul J. Fishman said today.