DECATUR, Ill. (AP) _ A senior Archer Daniels Midland Co. executive who went undercover for a government investigation of possible price-fixing by leading food processors was fired over allegations that he stole at least $2.5 million.

Mark Whitacre, 38, a young executive once touted as ADM's future president, was fired Monday. The company referred the case last week to the U.S. Justice Department, which has opened a preliminary criminal investigation, spokesman John Russell said in Washington.

The firing was the latest strange twist in the relationship between the nation's largest grain processor and Whitacre.

Whitacre, 38, who headed ADM's BioProducts Division, was a government informant for three years, using tiny video cameras and tape recorders to record private meetings between ADM and grain-industry competitors in the United States and abroad.

Whitacre's attorney, James Epstein, however, had predicted his client would be fired.

``Now we see the focus being turned on Mark Whitacre, rather than the wrongdoing he captured on tape,'' Epstein said Monday. ``The wrongdoers are attempting to benefit by having the investigation shift away from them to Mark Whitacre.''

Whitacre did not return phone messages seeking comment on his dismissal.

Whitacre has been barred from company headquarters since his role as an informant was made public July 10. A week later, ADM told Wall Street analysts that he still was on the payroll.

ADM and three other U.S. grain processors have said they are targets of a federal investigation into possible price-fixing in the markets for citric acid; corn-syrup, a high-quality, cheap form of sugar that is used in soft drinks, chewing gum and flavored iced teas and juices; and lysine, an amino acid that speeds up growth in swine and poultry.

The Justice Department to date has refused to comment on the investigation or say which companies are under investigation.

Besides ADM, other companies to disclose they are part of the antitrust investigation are A.E. Staley Manufacturing Co., also based in Decatur, CPC International Inc. of Englewood Cliffs, N.J., and Cargill Inc. of Minnetonka, Minn.