David Schippers, the Republicans' prosecutor, blasted into your living rooms on your TV sets attacking the President and passionately calling for his impeachment over the Monica scandal.

But Schippers -- who has 10 children and a wife of 45 years - hid something from you. Sitting behind him on the floor of the House Judiciary Committee was his secret mistress of 25 years.

Schippers, 69, chief investigative counsel for the House Judiciary Committee, and his office manager Nancy Ruggero, 51, had an affair that ended when Ruggero finally married after waiting in vain for Schippers to follow through on a promise to leave his wife.

"It's an incredible hypocrisy!" a source who's known Schippers and Ruggero for years told The ENQUIRER. "He's sitting there with his former long-time mistress by his side, trying to have Clinton impeached!"

Several sources close to Schippers and Ruggero confirmed the affair and said at first they had believed that his sex life was nobody's business. But they could no longer remain silent, they said, once he began publicly moralizing about Clinton's alleged crimes.

Adding to the outrage, Schippers brought his ex-mistress AND his wife to the Committee hearings at the same time!

Schippers studied for the priesthood before marrying wife Jackie, "his one and only sweetheart," according to a "60 Minutes II" profile broadcast on January 13.

That report also noted "the Senate impeachment trial owes its very existence to one man" -- Schippers.

In another profile in the Sept. 7, 1998, New Republic, Schippers told the magazine: "There should be a moral overtone to every profession. The rules are the rules are the rules."

And when asked by the magazine if adultery was a mortal sin, Schippers said adultery is, indeed, a mortal sin.

Schippers is a papal knight, an honor granted to only a few hundred Catholics.

But sources painted him as more of a hypocrite than a saint.

And in an ironic parallel to the Clinton case, Schippers may have to answer under oath whether he had an affair with Ruggero. Both are being sued for business fraud by a former partner who hopes to prove that the affair played a part in the alleged fraud!

The source revealed that Schippers and Ruggero, a former flight attendant, started their affair in the early 1970s, when Nancy was in her early 20s -- the same age as Monica Lewinsky at the outset of her affair with the President. "Nancy was hired to work for Dave's partner" at the Chicago law firm of Schippers & Bailey, the source told The ENQUIRER. "Her job evolved into working for Dave part-time, and that's when the affair started. Dave already had a bunch of kids, and his wife Jackie stayed home with them when they were young.."

"For the first few years of the affair, at least, I know Dave and Nancy would go on business trips together. "Dave, who lives in a suburb, would take the train to work in the early morning and get off at a stop near Nancy's home instead of continuing on to his downtown office. "That's mostly where the affair occurred, though they would arrange to meet each other in other places on occasion.."

"Dave over the years gave Nancy gifts -- a lot of diamonds and gold jewelry. Plus he put together a nice little stock portfolio for her. "Nancy for years pretended to everyone that she was going out with a married man who had separated from his wife. She even referred to him as 'Dave.'

"Nancy kept waiting for Dave to leave his wife, and he told her he would -- but of course he never did.

"Dave's wife caught on to the affair. Because of Jackie's suspicions, she had a family member follow Dave on a weekend bike-riding session.

"Dave left his home and, lo and behold, wound up at Nancy's home on Chicago's north side for a little rendezvous. "Then after an hour or two it was back on the bike and home to Jackie and the kids. "I believe that's how Jackie found out about the affair for sure, but Jackie knowing about the affair didn't make it go away. I guess Jackie made peace with it.."

"Dave's wife and children hate Nancy, as you would expect. But they've had to make room for her, because Dave didn't give her up.."

"Nancy finally got tired of Dave's promises and married Al Tracy, a former IRS investigator, three years ago.."

"Dave wasn't happy about Nancy marrying, though he knew and liked Al.."

"Even on her wedding day, Dave played a part. He was running late and didn't arrive until 15 minutes past the scheduled hour for the wedding ceremony. "Nancy insisted that everything be halted until Dave could be there to see her walk down the aisle! "I'm certain Al, who works as an investigator for the law firm, knew all about her affair with Dave. But Nancy called things off with Dave before she started going out with Al."

Nancy still works for Schippers -- at taxpayers' expense. "Though the affair is over, Dave still needs Nancy professionally -- and she is certainly well- compensated by him," said the source. "She gave up the chance to have a husband and children in order to be his mistress for 25 years, but in the end she's done all right."

A former co-worker of Schippers confirmed the extramarital affair and told The ENQUIRER that David at one point considered retirement and wanted to make sure that Nancy would be taken care of financially. "Dave hit on the idea with her of starting a process-serving business and enlisted several investors to start up the business.." "Nancy was named president of the business."

But in 1997 one of Nancy's partners, Mickey Veich, filed suit against Nancy and the other partners -- including Schippers - for fraud and deceptive business practices. "Mickey wants to establish that Schippers' intimate relationship with Nancy, and his desire for her to be taken care of, was behind the alleged fraud," said the former co-worker.

And when Veich's attorney Colleen McLaughlin tried to delve into the nature of the relationship during a deposition, her questions went unanswered because the opposing attorney objected.

McLaughlin told The ENQUIRER: "I asked a number of questions of a personal nature regarding a relationship between Schippers and Ruggero."

McLaughlin said the nature of Schippers and Ruggero's relationship "could get very relevant" as the lawsuit moves forward.

Schippers led the charge to impeach Clinton.

When House Republicans lost seats in the November election and began to waver in the impeachment drive, he convinced them to continue the process. "What I said is, 'They're at a crossroad.' They're either going to stand up and do their duty, or they're going to be cowardly about it and walk away because of the polls," he told "60 Minutes."

A Chicago legal source told The ENQUIRER: "Dave and Nancy had a long affair, and now to see him stand there and be holier than anybody is galling. "If he instead had said, 'We all sin and make mistakes,' fine. Instead, he moralized. Seeing him on '60 Minutes' made me want to throw up!"

Another source added: "Dave's affair with Nancy was nobody's business until he got on his high horse and started moralizing about what Clinton had done. "Dave Schippers is a hypocrite, and should be ashamed of himself."

-- SPECIAL ENQUIRER INVESTIGATION By JIM NELSON