The fix was as simple as it was illegal, federal prosecutors say.

Minutes after receiving a $1,000 cash donation for his judicial campaign, Philadelphia Municipal Court Judge Joseph C. Waters Jr. explained to the donor just what she had bought.

"You run into a problem with any of your people, you get a hold of me," the judge told her. "Anything you need. Anything I can do to help you or anybody that you're interested in. All you do is pick up the phone and call me . . . anytime."

He didn't know that the FBI was listening.

Waters, 61, pleaded guilty Wednesday to federal mail and wire fraud charges, a day after he abruptly resigned from his office after five years on the bench.

In a hearing before U.S. District Judge Juan R. Sanchez, he listened soberly as his words were read aloud from transcripts of an FBI wiretap. He admitted that on two occasions he traded influence on cases before the court in exchange for help funding his bids for office.

"Guilty, your honor," Waters said in a forceful voice when Sanchez asked for his plea.

That 2010 conversation with the $1,000 donor, which took place only months after Waters was sworn into office, marked the beginning of his undoing. Court filings suggest Waters' downfall was shepherded by a cast that included a midlevel player in Philadelphia Democratic circles as well as a federal agent posing as a criminal facing fabricated firearms charges.

His downfall has jeopardized the careers of two other members of the Municipal Court bench. Late Wednesday, the Pennsylvania Supreme Court ordered the suspension of Judges Dawn Segal and Joseph O'Neill, whom Waters admitted turning to in seeking preferential treatment for his friends.

Waters, a former Fulbright scholar and Philadelphia police captain who was appointed to the bench in 2009 by Gov. Ed Rendell, declined to comment Wednesday. His lawyer, Michael J. Engle, characterized his client's actions as a momentary but serious lapse in judgment.

"Judge Waters is both embarrassed and ashamed of his conduct, and he's very remorseful," the lawyer said. "He understands that there's a punishment due."

The long-running investigation was led by Richard Barrett, the federal prosecutor who oversees public corruption prosecutions in the region. He was joined by Assistant U.S. Attorney Michelle Morgan and FBI Special Agent Eric H. Ruona.

While prosecutors did not name Segal and O'Neill in Waters' plea documents, their identities were clear from Municipal Court records.

Neither judge was alleged to have taken money in connection with Waters' admitted role in the two cases. There was no indication that either would face criminal charges, though top court officials said they could face administrative sanctions.

A woman who answered Segal's phone Wednesday said only, "The judge is not available." O'Neill declined to comment.

Also unnamed throughout Wednesday's proceedings was the "politically active businessman" who figured in both of the cases which Waters admitted interfering with.

Sources close to the case have identified him as Samuel G. Kuttab, a frequent Democratic donor who routinely hosted elected officials for dinners and at the time ran several businesses, including a real estate management and security firm.

In an interview Tuesday, Kuttab described Waters as a close friend but said he never asked for his help on court matters. "I would never put him in a position like that," he said. "I think that would have tarnished my relationship with him."

But prosecutors say he did exactly that. First, they say, he put the judge in touch with the $1,000 donor, who received Waters' promises of help and later came to the judge with a legal problem of his own.

Kuttab did not know at the time that the donor, whose name was also withheld by prosecutors, was working with the FBI. For months after that first cash donation, she continued to give gifts and money to the judge, according to court documents.

Under state law, donors are barred from giving more than $100 in cash to any candidate. Waters did not report any of the donor's contributions on his campaign finance forms.

By May 2012, she sought to cash in on her generosity, court documents say. She alerted Waters to a pending felony gun-possession case against a man she claimed was a cousin of a business associate.

Waters came through on those earlier promises, court filings say. He alerted Segal, who was set to hear the case, that one of his "friends" would soon appear before her court and asked Segal to "help him."

Unbeknownst to either judge, the "cousin" was an undercover federal agent and the charges against him had been staged.

When the case came up for a hearing in July 2012, Segal reduced the felony gun charge to a misdemeanor - a ruling federal prosecutors said Wednesday was made "without a proper legal basis."

Kuttab, too, allegedly took advantage of Waters' willingness to help out his donors.

When Kuttab's business was sued in 2011 by Montgomery County-based Houdini Lock & Safe Co. over a $2,700 debt, he turned to Waters in hope of securing a favorable ruling, federal authorities said.

Once again, Waters turned to Segal, whose court was scheduled to hear the case. She granted Kuttab a delay.

When the case again came up for a hearing before O'Neill, Waters again weighed in.

In a wiretapped conversation quoted in court filings Wednesday, the two judges discussed the case on the day the trial began - but only in oblique terms.

"He's a friend of mine, so if you can take a hard look at it," Waters told O'Neill, regarding Kuttab's involvement in the case.

"No problem," O'Neill was quoted as replying.

Hours later, court records show, O'Neill found in Kuttab's favor.

But prosecutors say Waters did not stop there. When Houdini threatened to appeal, Waters suggested that Kuttab settle with the firm to avoid the scrutiny of a higher court.

In the end, Kuttab paid Houdini $600 of the $2,700 it said he owed.

Prosecutors have remained silent regarding Segal and O'Neill's connections to Waters' crimes. Since there is no allegation that they took anything in exchange for their rulings, sources close to the investigation say it is unlikely they will face criminal charges.

The conduct alleged in Waters' plea documents may violate state judicial ethics rules prohibiting judges from discussing the cases before them with anyone outside of the courtroom.

But attempts to prosecute similar cases without a clear quid pro quo have come up short in Philadelphia federal court.

Last year, prosecutors charged nine judges with fixing tickets for friends, family, and political allies at Philadelphia Traffic Court. Three pleaded guilty, but the six that took their cases to trial convinced jurors that with no money or other benefits changing hands, extending favors from the bench was not a federal crime.

Whether Waters' plea leads to charges against others, state Supreme Court Chief Justice Ronald D. Castille said the alleged behavior of all three judges was a poor reflection on the courts.

"It's another terrible black eye for the court system," Castille said.