Frank Beyer, a modest accountant who helped unravel Ponzi schemes and bring down drug cartels as a U.S. Treasury investigator, died Feb. 21 of heart disease, his family said. He was 78.

Armed with an accounting degree from California State University, Sacramento, in 1961, Mr. Beyer began working as an Internal Revenue Service auditor before transferring to the Criminal Investigation Division as a special agent. He became a certified public accountant and played a key role in the investigation of major fraud and drug cases until he retired in 1989.

He helped prosecute owner Frank Monaco of Golden Plan of California, the third-biggest mortgage broker in the state, which was a Ponzi scheme that collapsed in 1982. He was involved in Operation Deep Snow, a 20-month, undercover investigation that led to the 1989 arrests of the mayor of South Lake Tahoe and 19 others on charges of cocaine trafficking, money laundering and conspiracy.

Although he carried a badge and gun, Mr. Beyer was an unassuming man who focused on crunching numbers rather than breaking down doors. As a rare CPA in law enforcement, he recalled that gangster Al Capone ultimately was arrested and sent to prison for tax evasion.

"There wasn't a lot of bravado in his work," said his son Kent. "He was a special agent, and that was part of it. But for him, it was a chess game. He was into figuring out all the angles of a crime."

Even so, Mr. Beyer never shied away from tough assignments. During Operation Deep Snow, he went undercover to meet with drug dealers in a boat on Lake Tahoe. In another case, he mopped floors for three days disguised as a janitor in a post office to nab a tax cheat at a mail drop.

"He was really good at being undercover," said his daughter Jill Blodget. "He would grow beards, wear sloppy clothes, do whatever he needed. He was really good at blending in."

Mr. Beyer served as a Treasury agent on dignitary protection details for President Jimmy Carter and his wife, Rosalynn, Sen. Ted Kennedy and Nancy Reagan. He testified in federal court as an expert on accounting and taxation.

Born in 1934 in St. Helena, Frank Otto Beyer was an 11th-generation Californian. He traced his family's history through his paternal grandmother, Mary Magdalene Vargas, to Jose Manuel Valencia, who arrived with Spanish explorer Juan Bautista de Anza in 1776.

He graduated from St. Helena High School and served in the Navy during the Korean War. A son and grandson of barbers, he worked part time cutting hair to supplement his GI Bill funding to attend Sacramento State and was a member of the first graduating class of the College of Business Administration.

He was married for 57 years and had three children with his wife, Elsie. A Rancho Cordova resident, he enjoyed gardening, hunting and fishing and was devoted to his dogs.

In 2011, Mr. Beyer was among six alumni of the class of 1961 who were honored on the 50th anniversary of the CSUS business school. As the first member of his family to graduate from college, he was proud that all of his children also earned college degrees.

"He had to sell his favorite fishing pole to pay for books," Blodget said. "He was very devoted to education."

Call The Bee's Robert D. Dávila, (916) 321-1077. Follow him on Twitter @Bob_Davila.

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