Kaboni Savage, described by a federal prosecutor as the leader of "perhaps the most violent drug gang ever seen" in Philadelphia, pleaded not guilty this afternoon to racketeering and murder charges.

Savage, a former boxer and convicted North Philadelphia drug kingpin, appeared at an arraignment hearing before U.S. District Court Judge R. Barclay Surrick. The one-time professional boxer said little during the session.

Dressed in green prison garb and with shackles on both his hands and ankles, Savage sat quietly through the brief court proceeding. He stood and said, "Not guilty," when the charges were read.

His lawyer, Christopher Warren, said after the hearing that the case was built around "corrupt, polluted, self-serving sources."

Warren said he would attempt to block an expected Bureau of Prisons move to send Savage back to the maximum security prison in Florence, Colorado, where he is currently serving a 30-year sentence.

Warren said he wanted Savage to remain in the Federal Detention Center in Philadelphia in order to prepare for the new trial.

Savage is charged with heading a cocaine trafficking operation that used murder and threats of violence to control narcotics trafficking and to intimidate and eliminate potential witnesss.

Already serving a 30-year prison sentence for a drug trafficking conviction in 2005, Savage, 36, was brought back to Philadelphia from a federal prison in Florence, CO, to face the new round of charges which includes cocaine trafficking and murder.

He and three co-defendants were named in a 26-count indictment handed up in April. Each faces a possible death sentence.

Savage is charged with participating in 11 or the 12 murders listed in the indictment, including ordering from prison the firebombing that left six people, including four children, dead.

Two co-defendants, Lamont Lewis and Robert Merrit, are charged with carrying out the arson on Savage's orders. Authorities allege that Lewis and Merrit set fire to the North Philadelphia rowhouse of Carmella Coleman in October 2004.

Coleman was the mother of Eugene "Twin" Coleman, a former Savage associate who was cooperating with federal authorities.

Carmella Coleman, another woman and four children ranging in age from 15 months to 15 years, died in the early morning fire. The infant was Eugene Coleman's son Damir Jenkins.

The case against Savage is built around informant testimony and secretly recorded conversations, including dozens picked up on an electronic listening device hidden in Savage's prison cell at the Federal Detention Center on Arch Street while he was awaiting trial in the 2005 drug trafficking case.

The tapes include graphic and expletive-laden rants in which Savage vows revenge on witness and their families. He also jokes about the victims of the firebombing, suggesting that Eugene Coleman should have brought barbecue sauce to their funerals.

Coleman testified against Savage in the 2005 trial and is expected to testify again in the pending case.

Contact staff writer George Anastasia at 856-779-3846 or ganastasia@phillynews.com.