When investigators raided the West Philadelphia office of abortion doctor Kermit Gosnell in February 2010, it was to check out if he was illegally prescribing dangerous pharmaceuticals.

Once inside, however, agents were confronted by a more pressing issue: a "charnel house" of stored and dismembered fetuses - evidence that Gosnell's Women's Medical Society performed illegal late-term abortions.

On Wednesday, the probe of the 70-year-old doctor came full circle as a federal grand jury accused Gosnell and three clinic workers of selling prescriptions for almost a million pills containing the narcotic painkiller Oxycodone and the generic version of the antianxiety drug Xanax.

Those two drugs and scripts for more than 19,000 ounces of codeine-based cough syrup - all coveted by addicts - were allegedly sold for cash out of the clinic at 3801 Lancaster Ave. from 2008 through January 2010 under cover of what Gosnell called his "pain management practice."

Gosnell - in prison without bail awaiting trial in Common Pleas Court on murder and related charges in the abortion clinic's operation - was indicted with ex-employees Sherry L. West, 52, of Newark, Del., and Tamirrah M. Fluellen, 23, and Kareema B. Cross, 26, both of Phila.

Gosnell, West, and Fluellen are charged with conspiracy to distribute controlled substances, varying counts of distributing the drugs, and distribution of drugs within 1,000 feet of a school. Cross is charged only with distributing Oxycodone.

Gosnell alone is charged with running a continuing criminal enterprise, which carries a mandatory minimum 20-year prison term on conviction. Prosecutors are asking him to forfeit at least $200,000 - the alleged profit from the pill mill.

"You are talking about very serious, highly addictive, frequently abused sedatives and painkillers," said Assistant U.S. Attorney Jessica Natali.

Natali noted that the indictment alleges that Gosnell started in 2008 writing several hundred bogus prescriptions a month. By January 2010, Natali added, Gosnell was writing more than 2,300 scripts a month for the drugs.

Defense attorney Jack McMahon, who is representing Gosnell in the state case, said he would also represent him in the federal case.

"We knew this was coming, obviously," McMahon said. "I haven't seen the indictment and I really haven't been focusing on the federal investigation."

The state charges facing Gosnell include murder in the death of a Virginia woman administered too much anesthesia during an abortion, as well as the deaths of infants born viable.

Common Pleas Court Judge Jeffrey P. Minehart set March 2013 for a trial expected to last 10 weeks. Gosnell could be sentenced to death if the jury finds him guilty of first-degree murder.

The U.S. Attorney's Office also announced the filing of charges against four others in the operation of the "pill mill": Lynda G. Williams, 43, of Wilmington, a clinic worker who assisted Gosnell in performing abortions; Steven E. Massof, 49, an unlicensed physician who has admitted performing illegal abortions; and clinic workers Earlene "Tina" Baldwin, 46, and Latosha Lewis, 29, both of Philadelphia.

The four were charged individually by the federal prosecutor in criminal informations, which means they have agreed to waive indictment by the grand jury. The process is used when the defendant intends to plead guilty.

Williams, Massof, Baldwin, and West were among eight clinic workers charged in the state case; all four have pleaded guilty and are expected to testify against Gosnell when he goes to trial with two other former employees not charged in the federal case.

Cross and Lewis were mentioned in the county grand jury report and testified before the grand jury about the performance of illegal abortions at the clinic. Neither was criminally charged.

Contact staff writer Joseph A. Slobodzian at 215-854-2985, jslobodzian@phillynews.com, or @joeslobo on Twitter.