Updated: 4:55 p.m.

The special counsel hired by the Senate Ethics Committee concluded that there is “substantial credible evidence” that former Sen. John Ensign violated federal civil and criminal laws, as well as Senate rules, during the disintegration of an extra-marital affair with the wife of an ex-aide and close family friend.

In a report released Thursday, the Ethics Committee reported the findings and referred the matter to both the Justice Department and the Federal Election Commission, which could choose to take further action.

Both Senate Ethics Chairman Barbara Boxer (D-Calif.) and Vice Chairman Johnny Isakson (R-Ga.) took the unusual step of speaking on the Senate floor Thursday afternoon about what Boxer called an “extensive” 22-month investigation into the embattled Nevada lawmaker’s actions that required 32 subpoenas, the testimony of 72 witnesses and the review of more than a half million pages of documents.

Had Ensign not resigned from his Senate seat May 3 — on the eve of the day he was scheduled to testify before the Ethics Committee — the Nevada Republican’s actions would have warranted expulsion from the Senate, the harshest penalty the Ethics Committee could recommend, the special counsel concluded.

“While Senator Ensign’s resignation ended our investigation before the next phase … it did not end our profound responsibilities,” Boxer said on the floor. “This Ensign case was a sad chapter for the Senate.”

Ensign’s legal team said the former Senator is “confused and disappointed” that the committee chose to issue its report without giving further consideration to Ensign’s written submission, which it received yesterday.

“Given his resignation and announcement that he was not running for re-election, there does not seem to be any real reason for a rush to create a report,” said Robert L. Walker of Wiley Rein and Abbe D. Lowell of Chadbourne & Parke in a joint statement.

Ensign began his affair with Cynthia Hampton, wife to ex-aide Doug Hampton and an one-time employee of the former Senator’s campaign committee and leadership PAC, in 2007 following a break-in at the Hampton family home. After the Hamptons moved in with the Ensigns in their house outside Las Vegas, Ensign began pursuing Ms. Hampton aggressively, and the two began an affair. Several months later, Ensign told Mr. Hampton he could no longer work with him, as he was in love with his wife and wanted to marry her, the special counsel’s report shows.

Shortly thereafter, Ensign began “pressuring contributors and constituents to hire Mr. Hampton even though he had no public policy experience or value as a lobbyist other than access to the Senator and his office” and his personal journal entries revealed that the Hamptons received a $96,000 severance payment via Ensign’s parents, according to the report.

Mr. Hampton was indicted in March for lobbying Ensign during a mandated cooling-off period after leaving the Hill. Ms. Hampton has since filed for bankruptcy and divorce.

“The committee believes that every Senator should read this report very carefully because it is a cautionary tale. It shows that our actions — all of them — have consequences for ourselves, our families, staffs and for our nation,” Boxer said.

The report also raises questions about the role Sen. Tom Coburn (R-Okla.) played in the matter. Coburn is said to have reached out to Ensign’s father in an effort to stop the affair and then tried to broker a monetary settlement between Mr. Hampton and Ensign, according to Hampton’s lawyer. Coburn testified that he did not propose any solutions and merely passed information between the two parties. His office declined to comment on his role in the aftermath of Ensign’s affair.

Though the Justice Department has not indicated whether it will investigate Ensign further, Boxer seemed confident that the committee’s findings will result in legal action.

“The Justice Department will look at it, they have to,” Boxer said to a group of reporters.

Steven T. Dennis contributed to this report.