DENVER -- Edward W. Nottingham, the chief federal district judge in Colorado who oversaw the insider trading trial of former Qwest Communications CEO Joe Nacchio, is resigning amid complaints that he had asked a prostitute to lie about their relationship.

Nottingham had been under investigation for alleged judical misconduct for some time. Allegations that he was frequenting porn sites in the judge's chambers, visiting strip clubs and using the services of prostitutes surfaced last year during a divorce.

Early last week, he was notified of a new official misconduct complaint filed by a prostitute that alleged he asked her to lie to investigators about months of ongoing sexual relations.

Chief Circuit Judge Robert H. Henry released a statement Tuesday afternoon confirming Nottingham's resignation. The resignation goes into effect immediately, the statement said.

The statement, posted on the Web site of the 10th U.S. Circuit Court, said misconduct proceedings have been initiated against Nottingham and that he was stepping down "at this critical time in the investigation of these multiple complaints of misconduct."

Henry did not elaborate and said he would have no further comment.

Nottingham said in a statement, released through his attorney's office, that he resigned because it was in the best interest of all involved.

"It is in the public interest and the interest of the federal judiciary because it will terminate his judgeship and begin to restore public confidence in an institution which he profoundly respects," said a statement released from Nottingham's attorney, Stephen Peters.

The statement also said Nottingham is "deeply remorseful for his actions. He is also embarrassed and ashamed for any loss of confidence caused by those actions and attendant publicity and sincerely apologizes to the public and the judiciary."

U.S. Sen. Ken Salazar called Nottingham "one of the most skillful lawyers and jurists I have known."

"I am saddened by the allegations and it is right that he resign," Salazar said in a statement. "He has done what is in the best interest of the United States District Court for Colorado."

Judge Wiley Y. Daniel succeeds Nottingham as chief judge, Henry said.

President George W. Bush appointed Nottingham to the chief job on the federal bench, which is a lifelong appointment. Nottingham submitted his letter of resignation to the president Tuesday.

Salazar said his vacancy would probably be filled sometime in 2009. Salazar said he would work with his colleagues when they return to the Senate to make sure a new judge was appointed as soon as possible.

It would have taken an impeachment by the Senate to remove Nottingham from the bench if he had not stepped down.

Attorneys React To Nottingham's Resignation

Nottingham, a native of Eagle County in the Colorado mountains, took up his position on the federal bench in November 1989. He became chief judge of the U.S. District Court for Colorado last year.

Nottingham was known for his bursts of temper and a cutting manner, and he'd punish attorneys he considered to be unprepared by holding trial review sessions at 6:30 a.m.

"I don't think he has a lot of patience for people who aren't prepared," said Donald Lozow, an attorney who has had dozens of cases before Nottingham over the years. "His patience is not good."

Richard Kalamaya, a trial lawyer from Longmont, attended law school with Nottingham from 1970 to 1972. He said the judge was a good student known for his arrogance.

"He's one of those guys that carries himself like you would think a federal judge would carry himself, but with an air of arrogance and untouchableness," Kalamaya said.

"He is truly one of the brightest minds on the federal bench. But the problem that Judge Nottingham has consistently had is that of his judicial temperament," said attorney David Lane, who had several cases before Nottingham. "Judge Nottingham's arrogance has always been a problem, that and the disdain he shows for litigants."

Jeralyn Merritt, a federal defense attorney who has worked with Nottingham for 17 years, said he "is a very bright, professional judge."

"He always gave a fair trial. He was a little tougher in sentencing that I would have liked but I am sorry he's resigning," Merritt said.

Merritt has two pending cases before Nottingham. She said he made her a better lawyer by demanding all attorneys be prepared in the courtroom.

The three-times divorced father of three is an active skier and cyclist. He received a law degree from the University of Colorado and served as an assistant U.S. attorney in Denver for nine years before going into private practice in Grand Junction.

Accusations Of Misconduct Surfaced Last Year

In 2007, a federal investigation revealed Nottingham's alleged involvement with Denver Players, a high-end prostitution ring. The U.S. District Attorney's Office said no charges had been filed against Nottingham in relation to the case, though.

Sean Harrington, who heads a legal technology firm, filed a complaint in January citing news reports that Nottingham allegedly viewed adult Web sites on his government computer in his chambers.

Harrington also alleged that Nottingham had testified in his own divorce case that he spent $3,000 at a strip club.

Another complaint against Nottingham involved a September 2007 dispute over a handicapped parking space.

Nottingham illegally parked in the space and received a $100 ticket.

Guilty or not, many judges said they were shaking their heads over the claims. Former District Judge Jim Miller said it was "black-eye" to the profession.

"The judge may not have broken a law but it calls into question his fairness and objectivity as a judge," said Miller. "It undermines the confidence in the court."

Nottingham's resignation leaves the 10th U.S. Judicial Court in a pinch. There is already one vacancy that remains to be filled.