CAMDEN, N.J. (AP) _ Former Philadelphia mob boss Ralph Natale calmly pleaded guilty Friday to a three-decade criminal career that included seven murders, four attempted murders, extortion, gambling and drug trafficking.

``Were these acts committed to further the aims of the Philadelphia La Cosa Nostra?'' federal prosecutor Barry Gross asked Natale.

``They certainly were,'' answered Natale, believed to be the highest-ranking mob boss ever to cooperate with prosecutors,

Natale, 65, also pleaded guilty to bribing the mayor of Camden, conspiracy to distribute methamphetamine, and murder in aid of racketeering.

Natale, who ran the Philadelphia mob from 1994 until 1998, has been turning over compatriots to the government since his arrest last summer on drug charges. His help led to the indictment of his reputed successor, Joseph ``Skinny Joey'' Merlino, and 10 others in March on similar charges.

The government also plans to have Natale testify against Mayor Milton Milan, who in March was charged with accepting money, vacations, automobiles and home improvement work from Natale and mob associates.

``The cooperation of this major underworld figure has broken the mob structure and led us to some very fertile areas for further investigation and prosecution,'' U.S. Attorney Robert J. Cleary said in a statement.

Natale could face up to life in prison. Prosecutors said he would be spared the death penalty. A sentencing date was not set.

Natale's attorney, Marc Neff, said Natale hopes to get a reduced sentence in exchange for his cooperation. Prosecutors said they agreed to recommend a lighter sentence.

In court, though, U.S. District Judge Joseph E. Irenas warned Natale that he does not have to go along with the punishment recommended by prosecutors.

``If you don't like my sentence, that's not a ground to withdraw your plea,'' Irenas said.

Merlino's attorney, Edwin Jacobs Jr., on Friday called Natale's guilty pleas ``window dressing'' meant to bolster his credibility as the ``knowledgeable head of organized crime.''

``The fly in their ointment is that he's doing all this for a probable couple years in jail ... he could admit being responsible for the Hindenburg disaster,'' Jacobs said.

Michael Pinsky, lawyer for reputed South Philadelphia mobster George Borgesi, who was indicted with Merlino, said he attended Natale's hearing to ``watch the government make a deal with a serial killer.''

Pinsky and Jacobs said they plan to question Natale's motivation for cooperating with the government at their clients' trials.