Mark Whitacre, the Archer Daniels Midland Co. executive-turned-FBI informant, pleaded guilty yesterday to criminal charges of embezzlement, tax evasion and money-laundering -- admitting that he stole $9 million from the agribusiness giant while he was secretly taping conversations for the government.

For more than three years, Whitacre taped hundreds of conversations at ADM and at hotels and meeting places around the world where company officials met with competitors to fix the prices of three little-known food products. The FBI outfitted him with equipment worthy of a spy novel, including a concealed body recorder and a briefcase with a hidden video camera.

An embarrassed Justice Department, which supervised his spying, is now recommending that Whitacre spend 6 1/2 to eight years in prison for his fraud. It also asks that Whitacre, 40, repay the amount stolen -- a practical impossibility for a man who recently declared bankruptcy.

Whitacre stole money from ADM by submitting fake invoices while he was head of its bioproducts division -- and, for most of the time, an FBI undercover operative. He would turn in bills allegedly owed to various dummy contractors and vendors. Later, he would approve the payments. But the money actually went into several bank accounts established in the United States and the Cayman Islands in the name of the fake contractors.

Millions of dollars ultimately wound up in Whitacre's pocket, according to papers filed in U.S. District Court in Urbana, Ill.

The Whitacre scheme began in April 1991, according to prosecutors. When he began working for the FBI in 1992, he signed an agreement saying he would not engage in any criminal activity without the agency's approval. Federal agents and prosecutors did not know about Whitacre's theft of ADM money until ADM accused him in 1995.

Yesterday's guilty plea is the latest in a series of bizarre twists and turns in the ADM price-fixing case.

Whitacre at first presented himself as the ambitious but honest Boy Scout who became a government mole because he believed it was the right thing to do. Later, when ADM accused him of embezzling money, he claimed that the money he had in Swiss bank accounts was a result of a widely used ADM bonus plan to reward outstanding executives by giving them off-the-books compensation. Shortly after he was accused of pocketing the company's funds, he drove his car into the garage of his home, closed the door and left the car running in an alleged suicide attempt.

Although Whitacre is now a confessed thief, he was central to the government case that brought the giant ADM to its knees. A year ago, the Decatur, Ill.-based company pleaded guilty to price-fixing and agreed to pay $100 million, the largest criminal antitrust fine in history. The case also precipitated the retirement of Dwayne O. Andreas, the company's politically powerful president and chief executive; Andreas remains chairman, however.

After shareholder protests, ADM also put more outsiders on its board of directors, which had previously been heavy with Andreas family members and business and political cronies.

In court yesterday, Whitacre appeared relaxed and told U.S. District Judge Harold Baker that he has been under a doctor's care, has been diagnosed as manic-depressive and takes lithium, according to the Associated Press.

Asked whether he had studied the plea agreement, he replied, "For many hours I did." Questioned about whether he wanted to go ahead with the plea, he answered, "Very much, your honor," the AP reported.

Whitacre's guilty plea is not the end of the case for either Whitacre or ADM. In May, Michael D. Andreas, the chairman's son and heir apparent, and Terrance S. Wilson, who was Whitacre's boss, are scheduled to go on trial in Chicago along with Whitacre on charges of fixing prices. Whitacre's price-fixing trial will not be affected by his guilty plea in the separate fraud trial, according to U.S. Attorney Scott Lassar.

Each of the three defendants has pleaded not guilty to the price-fixing charges.

"Now that Whitacre has admitted stealing millions from ADM, I am hopeful that he will be available to shed light on his allegations of gross government misconduct in the antitrust case," said Reid Weingarten, an attorney for Wilson in the price-fixing case.

"What he {Whitacre} did today confirms that the lies he told about Mick Andreas are blown apart at the core," said John Bray, Michael Andreas's attorney. Bray said it is too soon to tell what impact the guilty plea might have on the price-fixing case.

Whitacre claims he destroyed tapes that might have helped ADM in the case, at the request of the FBI.

Defense lawyer Bill Shields, who is not involved in the ADM case, said the government's price-fixing case "sounds like it's dead on arrival."

"The guy's credibility is zero at this point," Shields said. "He's going to be testifying from a jail cell. . . . Any tapes that rely on him as a witness will be completely unreliable."

In cases using tape recordings, someone who did the taping usually is called as a witness to introduce the taped evidence.

Lassar, who is handling the price-fixing prosecution, said he did not see how Whitacre's guilty plea would affect his case.

Late last year, three international firms pleaded guilty to fixing prices with ADM and agreed to cooperate with the government's case.

The testimony of executives of those firms will be crucial. That's because, even without Whitacre, the other witnesses allegedly will be able to corroborate the government's charges that Wilson and Michael Andreas conspired with them to eliminate competition in certain world markets. CAPTION: Former ADM executive Mark Whitacre leaves courthouse in Urbana, Ill., after pleading guilty to embezzlement, tax evasion and money-laundering.