The plot thickens, and gets increasingly bizarre, in the case of Sen. John Ensign's affair.
The Nevada Republican, through a written statement by his attorney, admitted Thursday that his parents paid the family of his mistress nearly $100,000 last year.
The admission came shortly after Doug Hampton, his mistress' husband, first told a Las Vegas reporter that the senator paid his wife a hefty severance. Hampton also said that Sen. Tom Coburn, R-Okla., and others originally had urged Ensign to pay the Hamptons "millions."
Aside from Ensign's admission of payment Thursday, the Hampton interview has set off a chain of other accusations and denials, indicating that the Ensign affair -- which received relatively little attention when it first broke -- might have staying power.
Ensign appears to be following the questionable lead of South Carolina Gov. Mark Sanford, who drew additional attention to his already sensational affair with an Argentine woman by revealing juicy new details to reporters after the fact.
Citizens for Responsibility and Ethics in Washington, a watchdog group, called Thursday for the Department of Justice to order a criminal investigation into the matter. The group already had requested inquiries from the Federal Election Commission and Senate Ethics Committee.
The group's director, Melanie Sloan, told FOXNews.com that Ensign's admission of his parents' payment only reinforces the call for an investigation.
"It just makes John Ensign look all the worse," she said. "He's a senator, not a 12-year-old. Now he needs his parents to come in and clean up his mess?"
Doug Hampton is a former Ensign aide and his wife, Cindy Hampton, is a former Ensign campaign treasurer. In the new statement, Ensign attorney Paul Coggins said Ensign's parents made "gifts" to Doug and Cindy Hampton and two of their children, with payments totaling $96,000. Coggins stressed that the payments were legal and described them as an act of magnanimity.
"The payments were made as gifts, accepted as gifts and complied with tax rules governing gifts," he said. "After the senator told his parents about the affair, his parents decided to make the gifts out of concern for the well-being of long-time family friends during a difficult time. The gifts are consistent with a pattern of generosity by the Ensign family to the Hamptons and others.
"None of the gifts came from campaign or official funds nor were they related to any campaign or official duties. Senator Ensign has complied with all applicable laws and Senate ethics rules," he said.
The classification of the payments as "gifts" is critical in avoiding campaign finance law penalties.
Sloan said there would be nothing illegal about a gift, but there could be if the so-called gift was actually a severance payment. She said such a payment, even if made by the parents, could be seen as an in-kind contribution from the campaign committee that he should have reported. She said it would also be a problem if he exceeded the $5,000 contribution limit for PACs.
"Just because they say (it's a gift) today doesn't mean it was a gift then," she said.
And she said Coburn's got some explaining to do, since he apparently knew about the affair long before Ensign went public and allegedly urged Ensign to pay money. Sloan said there's nothing untoward about urging the senator to pay out, unless Coburn urged Ensign to do so in an illegal way.
Coburn on Thursday "categorically" denied Hampton's payment allegations, but at the same time Coburn says he's not going to testify about his advice.
Roll Call reported Thursday that Coburn is claiming that because he gave the advice as a "physician and as an ordained deacon," he doesn't have to testify. Roll Call reported that Coburn cited constitutional protections for religious counseling as well as for patient confidentiality.
Coburn, though, is an obstetrician, making it unlikely that Ensign was a patient in the traditional sense.
Doug Hampton alleged in the interview with a Las Vegas Sun columnist that Coburn was among those urging Ensign to pay millions of dollars to the Hampton family.
"These men were the ones that said what we need to do is get Doug Hampton's home paid for, and we need to get Doug Hampton some money. We need to get his family to Colorado," Hampton said.
Ensign's office also dismissed Hampton's interview.
"In response to today's television interview, Senator Ensign said Doug Hampton was consistently inaccurate in his statements," Ensign spokesman Tory Mazzola said in a statement Wednesday.
FOXNews.com's Judson Berger and FOX News' Trish Turner contributed to this report.