A physician accused of illegally selling prescriptions for the powerful painkiller oxycodone out of his car surrendered Thursday to face federal drug conspiracy charges.

Dr. Leonard Stambler made an initial court appearance in U.S. District Court in Central Islip and was ordered held without bail until a Monday hearing. His attorney, Gary Schoer, didn't enter a plea and declined to comment afterward on the charges.

The arrest comes amid a heightened awareness of prescription painkiller abuse following the massacre of four people inside a Long Island pharmacy in June. David Laffer, who pleaded guilty in the case, made off with thousands of hydrocodone-type painkillers after shooting two employees and two customers. He said at his sentencing last month to consecutive life prison terms that he hoped his case would lead authorities to examine the phenomenon of "doctor shopping."

Newsday reported that federal drug enforcement agents on Thursday raided the Great Neck offices of one of the physicians linked to Laffer. A spokesman for the U.S. attorney's office declined to comment on the report. Dr. Eric Jacobson told reporters outside his office that he had done nothing wrong, but he would stop prescribing controlled substances until the investigation is completed.

Prosecutors in the Stambler case say that at least 20 times from March to November, the physician gave prescriptions to patients who they believed were reselling or abusing the painkillers. There is no indication of any link between Laffer and Stambler.

Authorities said the 60-year-old Stambler didn't work out of a medical office but instead drove around to patients' homes to deliver the prescriptions. Assistant U.S. Attorney Alan Bode said Stambler's home in Baldwin Harbor was condemned on Thursday after authorities uncovered a filthy residence riddled with cat feces. He also had at least 50 air rifles in the home, Bode said.

Two weeks ago, authorities arrested a New York City pain management doctor whose patients included Laffer.

Prosecutors said Dr. Stan Li wrote more than 17,000 prescriptions -- mainly for oxycodone and other highly addictive painkillers. Li was charged with selling prescriptions to one patient even after the man repeatedly overdosed. An overdose ultimately killed that patient.

Li's lawyer has said the doctor denies the allegations.

Suffolk District Attorney Thomas Spota, who prosecuted Laffer, is seeking a special grand jury to investigate doctor shopping and possible criminal conduct by physicians in prescribing painkillers.