The U.S. government has offered $2.2 million to anyone who can help capture a Mexican fugitive accused of murdering an undercover U.S. agent during a drug purchase in 1994.

The record reward was posted Thursday for Augustin Vas-quez Mendoza, one of the FBI's 10 most wanted fugitives. Believed to be 26, he is a native of Apatzingan, Mexico.Vasquez Mendoza is thought to be hiding in Mexico, where agents suspect he fled after the June 30, 1994, killing of Richard Fass, an agent of the Drug Enforcement Administration.

Working undercover, Fass was fatally wounded in Glendale, Ariz., by henchmen of Vasquez Mendoza while buying 22 pounds of methamphetamine from them for $160,000, the government said.

"Special Agent Fass was murdered by Vasquez Mendoza and his criminal associates," said Drug Enforcement Administrator Thomas Constantine. "The two triggermen were arrested as they fled the scene and the third accomplice was captured in Los Angeles a few days later. The criminal mastermind, Vasquez Mendoza, escaped. We are committing all our resources to capturing this murderous coward."

Constantine said he hoped the sizable reward would bring in new leads and expected that "Vasquez Mendoza's days as a free man are numbered." DEA agents in Phoenix are operating a toll-free number, 1-888-853-4961, around the clock to receive tips.