A group of four former anesthesiology nurses at GW Hospital sued the University for overbilling the federal government in Medicare charges.

The nurses alleged that the hospital overcharged at least $100 million by assessing physician rates for procedures performed by nurses or residents in training, said Alan Grayson, the group’s attorney. They initially filed a False Claims Act lawsuit in federal court over a decade ago on behalf on the U.S. government, but the most recent complaint was filed earlier this month.

Linda Dent, a spokesperson for GW Hospital, said the University has acted legally in its billing process.

“We believe GW and its physicians acted appropriately, and the matter is being challenged,” Dent said in an interview Tuesday.

A lawsuit can be filed under the False Claims Act when a person “knowingly presents … to an officer or employee of the United States Government … a false or fraudulent claim for payment or approval,” according to U.S. Code 31.

Grayson said he’s currently investigating five issues in the suit’s amended complaint, which was filed earlier this month. He requested from the hospital about 10,000 Medicare documents, which he said have not yet been turned over.

The attorney said the University threw away the documents.

“GW destroyed all of their records of billing to the government while the hearing was pending,” Grayson said in a phone interview Friday.

Dent refused comment on the allegation of destroyed evidence and on other specifics of the case because of a hospital policy prohibiting speaking about pending litigation.

In several examples cited in the suit, physicians were playing computer games, resting in the hospital’s lounge and studying for exams instead of performing procedures that were billed to Medicare, according to The Washington Times. GW attorneys called the allegations that the anesthesiologists were not involved in billed treatment as “bald-faced distortions” in court records.

The next hearing in the case is scheduled for Nov. 2 in the U.S. District Court for D.C.

The GW Hospital is jointly owned and operated by the University and a subsidiary of Universal Health Services, Inc., one of the country’s largest hospital managements companies. The partnership began in July 1997, according to the hospital’s Web site.

-Kaitlyn Jahrling contributed to this report.