The sordid tale of former Sen. John Ensign (R) of Nevada is casting its dark ethical – and perhaps legal – shadow wider and wider in Washington.

Aside from the likelihood that Ensign will face criminal charges, recent revelations don’t paint a very good picture of Sen. Tom Coburn, former senator and presidential candidate Rick Santorum, nor the Justice Department.

When details of his affair with the wife of a former staffer and close family friend revealed what looked to many observers like a cover-up – including the payment of large sums of money via his parents – Ensign announced that he would not run for reelection. Then last week he abruptly resigned his seat in order to avoid having to personally face a Senate Ethics Committee investigation and his likely expulsion from the Senate.

This week, the bipartisan investigating committee, headed by Sen. Barbara Boxer (D) of California and Sen. Johnny Isakson (R) of Georgia, issued its scathing report.

“Based on the record in this matter, the Special Counsel respectfully submits that there is substantial credible evidence that provides substantial cause to conclude that Senator Ensign violated Senate Rules and federal civil and criminal laws, and engaged in improper conduct reflecting upon the Senate, thus betraying the public trust and bringing discredit to the Senate,” the report states.

Among other things, the report alleges that Ensign and his parents made illegal payments to his mistress and her husband, made false or misleading statements to the Federal Election Commission, and “permitted spoliation [alteration or destruction] of documents and engaged in potential obstruction of justice violations.”

The committee has referred the matter to the Justice Department and the Federal Election Commission.

Critics wonder why the Justice Department appears not to have pursued the Ensign case with any sense of vigor. Last December, the Justice Department informed Ensign's lawyers that he was "no longer a target" in a corruption probe.

“It is puzzling how DOJ, armed with the full might of the legal system, was unwilling or unable to reach the same conclusions as the ethics committee,” said Melanie Sloan, executive director of the watchdog group Citizens for Responsibility and Ethics in Washington, in a statement. “Perhaps this report will give DOJ the spine it so clearly lacks, and the courage to finally take on Senator Ensign.”

"It is only a question of when the government is going to indict," Douglas McNabb, a federal criminal defense attorney, told the Las Vegas Review-Journal Friday. "I don't understand why they set it aside before."

Meanwhile, Ensign’s personal disgrace and political downfall appear to have touched at least two of his Senate colleagues.

Former Sen. Rick Santorum (R) of Pennsylvania – who lost his reelection bid in 2006 and is now running for president on a platform stressing family values – learned of the Ensign affair in an e-mail from Doug Hampton, Ensign’s former chief of staff and husband of Ensign’s mistress, Cynthia Hampton.

Ms. Hampton reportedly was seeking Mr. Santorum’s help. But rather than reply to Hampton, Santorum forwarded the e-mail to Ensign, tipping him off to the impending scandal.

As the episode continued, Sen. Tom Coburn (R) of Oklahoma became involved in negotiating financial payment to the Hamptons (which involved Ensign’s parents) – apparently as a way of settling the situation in a way that would limit political damage.

As the Senate Ethics Committee report details, there’s much more to the story – including Ensign’s trying to generate lobbying business for Mr. Hampton after Hampton was pushed out of his job working for the Nevada senator.

None of it is likely to do any good to the reputation of Senator Coburn or to the presidential ambitions of Santorum.