Senate Finance Chairman Max Baucus continued his push for more aggressive tax enforcement today, seizing on the testimony of a convicted tax cheat to press IRS commissioner Mark Everson.

The Montana Democrat asked Everson why the agency can’t do more to prevent identity theft cases that lead to tax fraud, such as the crimes committed by Evangelos Soukas, a panel witness.

At the hearing, Soukas, now in federal prison, told the committee how he used stolen Social Security numbers to file fake tax returns and claim more than $40,000 in refunds.

Soukas said the IRS should require more proof of identification from taxpayers, such as a mother’s maiden name or a personal ID code.

Baucus called Soukas’s statement both riveting and disgusting.

“The story you tell is not one to be proud of, but there’s not much for the IRS to be proud of either,” he said.

Under intense questioning and interruptions from Baucus, Everson said he would explore the issues raised, but warned that requiring passwords or more security information for callers and electronic filers could cost money and cause problems.