Federal investigators have referred to the Justice Department an allegation that Dr. Arthur Hull Hayes Jr., commissioner of the Food and Drug Administration, received overlapping payments from the government and a private research group for a West Coast trip last year.

According to law enforcement sources familiar with the case, the inspector general's office at the Health and Human Services Department last week sent information on the Hayes trip to the U.S. attorney's office in Baltimore.

Inspector General Richard P. Kusserow's office decided there was a possibility of a criminal violation and asked the U.S. attorney to determine whether prosecution is warranted, the sources said. If the U.S. attorney decides not to pursue the matter, the case will be sent back to HHS for possible administrative action.

An FDA spokesman declined to comment, but Hayes has said that the payments were proper. "I haven't done anything wrong," he told The Washington Post earlier this month. "If I have, it has been absolutely inadvertent or because I didn't know some regulation."

Hayes' official speaking trip last April--which took him to Los Angeles, Seattle and Las Vegas--cost the FDA $903 in air fares.

While in Seattle, Hayes gave a private, after-dinner talk at Virginia Mason Research Center. He later wrote the center, asking that $832--which he said was for the equivalent of a round-trip, first-class ticket to Seattle--be sent to his Rockville home.

Hayes said in the letter that he would "sort things out with Uncle Sam," but he has not repaid the government for the air fare. Hayes has said that he used part of the payment from Virginia Mason to upgrade his tickets to first class, and that he sees no reason to repay the government for the additional air fare.

The research center also paid for Hayes' hotel and provided him with a $1,500 honorarium. Hayes was paid $4,300 in fees last year for addressing private groups on his own time.