Federal authorities charged Thursday that convicted South Philadelphia drug dealer and alleged mob associate William "Billy" Andrews went right back into the drug business after serving a 12-year sentence that ended in January 2009.

In fact, authorities alleged, Andrews was on supervised release in March 2009 when he began to sell prescription drugs - mainly oxycodone - on the streets of his neighborhood.

Andrews and two associates were arrested Thursday after they were named in a 47-count indictment charging them with conspiracy and drug distribution.

Andrews, 51, pleaded not guilty at his arraignment in U.S. District Court and was ordered held without bail. Two codefendants, Joseph Fareri and John Marshal, were also ordered held pending arraignments Tuesday. Each has filed for a court-appointed attorney.

Andrews, in jeans, windbreaker, and T-shirt and with his hands cuffed behind his back, nodded and winked at his son and brother, who sat in the small fifth-floor courtroom for the brief proceeding.

The indictment charges that between March 2009 and April 2011, Andrews conspired to distribute about 7,000 oxycodone pills, each selling for $20 to $30.

Andrews obtained the pills from "various sources," according to the indictment, including "a licensed physician who issued prescriptions [that Andrews used] to obtain oxycodone from licensed pharmacies."

No doctor or pharmacist has been charged.

The indictment also alleges that on several occasions, Andrews sold pills to cooperating witnesses who have subsequently testified before a grand jury.

Authorities said a number of drug sales were also made within 1,000 feet of schools, including St. Nicholas Tolentine in the 900 block of Pierce Street; SS. John Neumann and Maria Goretti High School in the 1700 block of South 10th Street; and the Stephen Girard Elementary School at 18th Street and Snyder Avenue.

The federal charges stem from an investigation begun by the Pennsylvania Attorney General's Office. In April, state investigators raided Andrews' Passyunk Avenue apartment and dozens of other locations.

Search warrants indicated the raids were part of an investigation into loan-sharking and the illegal sale of prescription drugs.

At the time, Andrews was described as the primary target of the probe.

Andrews, whose previous conviction was for dealing methamphetamine, has been identified by law enforcement sources as an associate of jailed Philadelphia mob underboss Joseph "Mousie" Massimino, currently awaiting trial on racketeering charges.

Documents in a related criminal drug case indicate investigators believe Massimino was providing money to Andrews to finance both a loan-sharking operation and the purchase of drugs.

Massimino has not been charged in the oxycodone case.

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