NEW YORK — The former head of the nation’s largest municipal jail guard union traded his duty to workers for a luxury handbag filled with cash, a prosecutor said Tuesday in opening statements at his bribery trial.

Assistant U.S. Attorney Martin Bell said Norman Seabrook accepted $60,000 in 2014 for funneling $20 million in union funds to a hedge fund. Seabrook, 57, has pleaded not guilty to conspiracy and fraud charges.

Bell said Seabrook conspired with his co-defendant, hedge fund financier Murray Huberfeld, to arrange the payoff while Huberfeld, 57, was looking for large investments to his 10-year-old hedge fund.

“This case is about how greed, pure greed, brought these two men together,” the prosecutor told jurors. Speaking of Seabrook, Bell added: “He sold his duty to the workers he represented once he saw an opportunity to line his pockets.”

Seabrook, suspended after his arrest, stepped down from his post at the New York City Correction Officers’ Benevolent Association.

He was hired in 1985 as a jail guard and within a decade had risen to the top of the union responsible for the retirement needs of 10,000 officers and thousands more retired officers. As the union boss, Seabrook was seen as having more influence over how the city’s Rikers Island jail complex operated than any other person, even the head of the city’s Department of Corrections.

“The proof will show that Norman Seabrook is innocent of these charges,” said defense attorney Paul Shechtman.

The lawyer said the government built its case on a star witness who is a pathological liar. He called his client one of the most effective labor leaders in city history.

Shechtman also said what mattered in the case was whether jurors will believe there was $60,000 in a Ferragamo handbag that was given to Seabrook.

Henry Mazurek, a lawyer representing Huberfeld, told jurors they would realize Huberfeld never suggested that Seabrook be given a bribe to secure what would have been a small investment in a billion-dollar hedge fund.

“It makes no sense,” he said.

He, too, attacked the main government witness, casting him as a “type-A personality” who bragged about his courtside seats to New York Knicks games and his close relationships with top city officials, including New York’s mayor.

“In a few days, he will lie to you to convict my client of a felony crime,” Mazurek said. “Ladies and gentlemen, don’t be another victim.”