A onetime office manager of a respected Rockville law firm pleaded guilty to theft Wednesday in what prosecutors described as a multiyear scheme to bilk her employer out of about $603,560.

Kelley Jo Hunt, who among other maneuvers gave herself large, undetected raises, faces up to 25 years in prison when she is sentenced next month. But the total probably will be considerably less, given state sentencing guidelines, her efforts to pay back the firm and what her attorney said was a clean criminal record.

Hunt has repaid $123,000 to the firm — Miller, Miller & Canby — and intends to pay at least $300,000 more. “The only meaningful expression of remorse, at this point, is action,” said Hunt’s defense lawyer, David Moyse.

Hunt spent the money on her family and on payments on a house that was worth less than what was owed on it, Moyse said. “There were no fur coats or fancy trips or extravagant items,” he added.

Hunt’s fraud went undetected for years. As to payroll records, she appeared to operate in a closed loop — administering records, working with an outside payroll vendor and reviewing reports the vendor sent back to the firm.

In January, though, one of those reports “went to another staffer, somebody in the accounting office of the law firm,” prosecutor Bryan Roslund said in court Wednesday. That report indicated Hunt had received about $5,000 too much. Managers confronted her. She said she’d also done it in the previous pay period and would repay $10,000, but she denied taking more.

“Unfortunately,” Roslund said, “that proved essentially to be the tip of the iceberg.”

The firm fired Hunt after the initial discovery, according to court records.

Investigators looked at records from the outside payroll vendor and Hunt’s bank account. Starting in at least 2008, Roslund said, Hunt inflated her wages and gave herself unauthorized overtime pay and at times simply created two checks for herself for a single pay period. The total take, according to Roslund, was $481,754. Hunt also dipped into the firm’s Flexible Spending Account, taking approximately $121,805, Roslund said.

Moyse acknowledged in court that Hunt took at least $425,000, but the exact total remains in dispute.

Founded in 1946, Miller, Miller & Canby works in land-use, tax, trusts and other legal areas. Four of its its members have served as president of the county’s bar association.

Another problem Hunt faces is that the victim she chose knows how to sue people.

In litigation filed in Montgomery County Circuit Court, Miller, Miller & Canby demanded $573,467.11 from Hunt that it said is still owed to the firm, plus punitive damages for fraud.

According to the lawsuit, Hunt became office manager in 2002. In 2008, she embezzled $17,399.79 in payroll funds, according to the firm. She made false entries into accounting and payroll records to cover her tracks.

The totals increased steadily, hitting $146,870.04 in embezzled payroll funds 2013, according to the lawsuit. Each year, according to the firm, she concealed the theft with false bookkeeping.

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