A man prosecutors described as a brutal drug kingpin whose retaliation against witnesses threatened the core of the judicial system was convicted Friday of drug charges, money laundering and witness intimidation.

A number of witnesses against Kaboni Savage, 29, have ended up dead, though Savage has denied any involvement.

In this case, the witness intimidation charges followed taped conversations in which Savage could be heard boasting about his reputation for violence and threatening to kill government cooperators and their families.

Five family members of one witness against him were killed in a fire in October of last year. Savage was jailed at the time, but authorities suspect he was somehow involved. The fire remains under investigation.

"If witnesses are silenced and intimidated, the whole system would eventually break down because no one would testify truthfully at trial," said Assistant U.S. Attorney Mark Ehlers.

The six-week trial included hundreds of secretly recorded conversations, many made at the Federal Detention Center in Philadelphia, where Savage has been held since last year.

Defense lawyer Christopher Warren said the jail is "a factory" for unreliable informants.

On the stand, Savage acknowledged making threats but said he had no way of carrying them out from behind bars. He also said he only supplied dealers with equipment, not drugs.

The jury found him guilty of conspiracy to distribute cocaine, money laundering, witness intimidation, and witness retaliation. He could face 20 years to life in prison.

Four other defendants were convicted of related charges.

The drug case had been the subject of intense news coverage in Philadelphia, even before the fire, because of its tangential connection to a federal public corruption probe that led to a bug in the office of Mayor John F. Street. The mayor has not been charged with any crime.

During the drug probe, FBI agents said they intercepted calls between dealers and the leader of an influential mosque. With a judge's permission, the FBI tapped the imam's home telephone, and allegedly recorded him discussing schemes to rig government contracts, connecting it to the corruption probe.