Rick Koerber’s real estate investment companies lost tens of millions of dollars over several years, an FBI forensic accountant testified Wednesday in Koerber’s federal court trial.

So instead of using business revenues to make interest payments, the operation used investors’ own funds, Angela Mennitt told the jury in Salt Lake City. During her testimony, aimed at bolstering the allegation that Koerber ran a Ponzi scheme, she traced monies through bank accounts, company books and promissory notes.

From 2005 to 2007, the group of companies Koerber oversaw in Utah County took in $98.5 million from investors but lost money on operations, Mennitt said.

“They had to rely on new investor monies to make interest payments to their investors,” Mennitt told the jury.

Koerber is facing 18 charges for his Utah County operation, which promised investors from 3 percent to 5 percent a month in interest. Prosecutors allege it was a Ponzi scheme when it collapsed in 2007.

Koerber pleaded not guilty and claims that his companies owned real estate that had a market value of $124 million, enough to pay investors before the real estate crash of 2007 sent home prices plunging.

Prosecutors had been expecting to rest their case Wednesday. But Mennitt was not done testifying when court adjourned for the day, and the government had one more witness who likely will take the stand Thursday.

Using a slide presentation, Mennitt summarized for the jury what she had found. As the companies brought in tens of millions of dollars, their obligations to make interest payments also shot up, she said.

“Interest expense kept building and building as more investment came in,” Mennitt said, while “there was very little income earned.”

On cross-examination, Koerber’s attorney, Marcus Mumford, jumped immediately into questions about whether Mennitt had included the market value of real estate the companies held in calculating their net worth.

She had earlier testified that companies’ own books showed that despite their real estate holdings, they had negative equity of $17.3 million.

But Mumford asked about the market value of those properties versus the price at which they were purchased.

He also suggested that in her analysis, Mennitt didn’t include substantial equity that was held in other Koerber-related companies.