Brown-Bunch displayed little emotion during the hearing. Rivera's family declined to speak afterward.
Rivera's remains were found Dec. 20. Police said a black plastic bag was knotted around the neck. It took a forensic analysis by New Jersey State Police to determine the identity.
According to the affidavit, an unidentified individual told detectives that Brown-Bunch beat Rivera with a "sharp instrument" and unleashed a pit bull on him in August.
The attack occurred inside a house in the 1700 block of Norris Street from which the drug set allegedly operated. Several months later, on Oct. 15, Rivera was reported missing.
In January, authorities searched the home and found blood in a second-floor bedroom. DNA testing later linked the blood to Rivera. Detectives also found bloody sweat pants with a Family First benefits card belonging to Rivera in the pocket. Rivera had last used the card in August, the affidavit said.
Brown-Bunch told detectives on Friday that Rivera had admitted taking $2,000 in drugs, which members of the drug set had noticed was missing, the affidavit said. Brown-Bunch told the set's members to "[expletive] him up," the affidavit said.
Inquirer staff writer Clark Mindock contributed to this article.