SALT LAKE CITY — The now ex-wife of a Utah rare coin dealer accused of stealing tens of millions of dollars in a silver trading scam told a federal judge Tuesday that she had no idea what her husband was doing until a month before authorities shut down their business.

But because she failed to tell police or investors, including her own family members, about Gaylen Rust’s alleged deception, Denise Gunderson Rust is headed to prison.

U.S. District Judge Ted Stewart sentenced Rust, 61, to 18 months behind bars and three years probation after she earlier pleaded guilty to money laundering. He also ordered her to pay restitution for $1.7 million she diverted from Rust Rare Coin, including a $12,000 check to her daughter, at her husband’s direction.

Denise Rust described herself as an “unwitting pawn in Gaylen’s world,” which prosecutors say included multiple affairs and online sex.

“I had no idea what Gaylen was doing was criminal,” she told the judge during a two-hour sentencing hearing.

A federal grand jury returned an indictment last year against Gaylen Rust, Denise Rust and their son, Joshua Rust, 37, of Draper, in connection with an alleged Ponzi scheme.

The Rusts bilked at least 700 investors of more than $150 million, prosecutors say. They are accused of tricking people into believing they were pooling their money to buy and sell silver bullion, but the funds were allegedly used to pay other investors and for personal use, including Gaylen Rust buying race horses.

All three were charged with wire fraud and money laundering conspiracy. Gaylen Rust is also charged with two counts of securities fraud. Denise Rust and Joshua Rust were also each charged with one count of money laundering.

Gaylen Rust owned and managed Rust Rare Coin Inc., R Legacy Entertainment LLC, R. Legacy Racing Inc., R Legacy Investments LLC, R Legacy Ranch, and Legacy Music Alliance. Denise Rust was listed as the secretary for Rust Rare Coin. Joshua Rust managed the coin shop from 2004 to 2018.

Some of the alleged fraud victims — inside and outside Utah — came to invest in the silver pool through their shared membership in The Church of Jesus Christ Latter-day Saints, according to investors’ statements in a civil lawsuit filed against Zions Bank in 2019.

During the time she worked in the office, Denise Rust signed 4,491 checks totaling $78 million, 80% of which went from new investors to old investors with the remainder going to other Rust businesses and personal use, the judge said.

As evidence that Denise Rust was unaware of her husband’s activities, defense attorney Walter Bugden said she signed checks to her husband’s mistress that totaled $3 million over a five-year period.

“She didn’t know the life that her husband was leading behind closed doors,” Bugden said. “She was a victim of Gaylen Rust.”

The couple were married but living separate lives for about six years before getting divorced earlier this year after 39 years of marriage.

Denise Rust said she didn’t know anything was amiss in the business until October 2018 when an attorney for one of Gaylen Rust’s clients loudly confronted him in his office about getting their money. She then learned her husband wasn’t doing what he told investors he was doing. She said he assured her everything would be fine with millions expected from another business venture called Musician’s Toolkit.

Denise Rust said she didn’t go to authorities or tell even family members that they were being duped because she trusted her husband and didn’t want employees to lose their jobs or investors to lose their money.

A month later, the Securities Exchange Commission shut down Rust Rare Coin in a civil complaint alleging a Ponzi scheme.

In hindsight, Bugden said Denise Rust should have gone to police. She didn’t make a perfect decision and didn’t understand her husband was running a Ponzi scheme, though she knew he had lied, he said. She thought the best way to help was to see if Musician’s Toolkit succeeded and could bail out investors.

Gaylen Rust was a “smooth talker,” Denise Rust said.

“He made people believe what he wanted them to believe, including me,” she said, adding she’s sorry she trusted him and that she didn’t see red flags sooner.

Budgen unsuccessfully argued that the judge sentence Denise Rust to five years’ probation.

Assistant U.S. attorney Jacob Strain argued she should go to prison, though prosecutors had only circumstantial evidence that she knew about the alleged fraud. He said one of the FBI agents who interviewed Rust believed she knew more than what she was letting on. He said she admitted to taking money from the business that wasn’t hers to take.

Prosecutors dropped the wire fraud charges against Denise Rust as part of a plea deal. She is scheduled to report to prison in November.

The criminal cases against Gaylen Rust and Joshua Rust are pending. The SEC complaint is on hold until the criminal cases are resolved.