Citizens for Responsibility and Ethics in Washington (CREW), the watchdog group which earlier this week filed an official complaint against Delaware Senate candidate Christine O'Donnell for her alleged use of campaign funds to pay for personal expenses, now has Sen. David Vitter (R-LA) in its sights.

CREW's complaint to the Senate Ethics Committee charges Vitter with "improper use of taxpayer funds to subsidize the personal expenses of staff member Brent Furer" and with issuing "demonstrably untrue statements about Mr. Furer's employment on his staff."

At the heart of the complaint is former Vitter aide Brent Furer, who resigned last June after ABC News revealed that "he had been arrested for attacking his ex-girlfriend with a knife, and had an open warrant for his arrest in Baton Rouge on a drunk driving charge."

According to ABC, "Vitter spokesman [Joel] DiGrado acknowledged the senator had concerns about the 2008 arrest, in which Furer was accused of holding his ex-girlfriend against her will for 90 minutes, threatening to kill her, placing his hand over her mouth, and cutting her in the hand and neck."

The Furer case appeared troubling from the start, in light of both his role in handling women's issues for the senator and Vitter's own previous involvement in a prostitution scandal. Since Furer's resignation, however, additional questions have been raised about the extent to which Vitter may have been aware of his aide's behavior and continued to support him despite it.

Although DiGrado claimed that Furer had been suspended from working for Vitter between his arrest in January 2008 and the resolution of his case that April, ABC noted in a follow-up story that "Vitter's office suspended Furer's pay on Jan. 17, five days after the incident. But his payments resumed on Jan. 22."

CREW, whose executive director Melanie Sloane was credited by ABC with having initially brought the Furer incident to their attention, has now taken the allegations against Vitter to a new level. "Taxpayers should not pay for violent criminals to go on holiday," Sloane asserts. "Yet it seems clear that Senator Vitter's idea of significant discipline for a women's issues staffer who stabbed and threatened his girlfriend is what most people would call a paid vacation. What could be more offensive than that?"

The formal complaint (pdf) notes that "prior to joining Senator Vitter's staff, Mr. Furer had a history of arrests for driving while intoxicated, possession of cocaine, and other offenses." It then goes on to point out that two trips which Furer made to New Orleans to deal with "personal legal matters" were paid for by Vitter's office expense account.

"Senator Vitter claimed through his spokesman he was not aware of Mr. Furer's driving while intoxicated charges until they were reported in the news media," the complaint continues. "This seems unlikely, however, given that at the time of Mr. Furer's October 2007 trip to Louisiana the Senate was considering a controversial amendment introduced by Senator Vitter related to immigration, an issue within Mr. Furer's legislative responsibilities. ... Presumably, Senator Vitter would have expected [Furer] to be present."

CREW also raises questions about whether Vitter helped Furer secure the services of a prominent criminal defense lawyer who represented him in his assault case and how Furer's was able to pay legal fees that would have amounted to about $530 an hour on his annual salary of $48,000.

Furer's attorney insisted to Talking Points Memo, however, that Furer's fees had been "minimal" because "It was a very small case, it was a nothing case. ... We went down to court, we entered a plea. The judge gave him a stern warning -- 'Behave yourself, otherwise I'll put you in jail.' And [Furer] cleaned himself up and is doing well."

Finally, the complaint suggests that Vitter himself may have been lying when he "insisted Mr. Furer was not assigned to women's issues," since both congressional directories and a statement from the executive director of the Louisiana Coalition Against Domestic Violence indicate otherwise.

"American taxpayers have a right to expect that their hard-earned dollars are spent on the people's business and not assisting a staff member facing criminal charges for drunk driving and domestic violence," the complaint concludes. "It is also reasonable to expect a senator to have the integrity to -- at the very least -- reassign an aide handling women's issues after he has pleaded guilt to criminal domestic violence charges. Finally, it is outrageous for a senator to blatantly lie about his legislative assistant's portfolio despite overwhelming evidence of his true responsibilities. Senator Vitter's continued protection of Mr. Furer -- a clearly troubled and dangerous person -- does not reflect creditably upon the Senate and merits the Committee's inquiry."