Tim Udinski was livid.

After one season as head lacrosse coach at Lansdale Catholic High School, he was out, ostensibly after conflicts with players and an assistant.

Udinski thought his dismissal was unfair, one the school wouldn't have considered for counterparts like veteran football coach Jim Algeo. So he launched a scheme to prove the point, authorities say.

Over seven months, Udinski allegedly sent anonymous e-mails to the Archdiocese of Philadelphia, claiming Algeo had solicited sex from a player and accusing the new lacrosse coach of sex assaults.

On Tuesday, Montgomery County prosecutors charged Udinski with harassment and stalking.

District Attorney Risa Vetri Ferman said his offenses were particularly galling because Udinski tried to manipulate a national spotlight on child-sex abuse in a vengeful bid to destroy reputations.

Detectives spent 184 hours on the case, interviewing students and staff and chasing the false rumors.

"The current publicity, it raises awareness, and that is a wonderful thing," Ferman said. "But the downside is that when accusations like this are made, they do so much damage. How do you undo that? How do you unring that bell?"

Udinski, 43, a Doylestown resident with years of coaching youth lacrosse around the region, hung up when reached by The Inquirer. According to an affidavit in the case, he confessed when confronted last month by detectives.

"I was mad at the school for the way I was treated. I was just furious," Udinski told them, the filing said.

The seeds of the plot may have been sown in March 2011, when Udinski himself was the target of false allegations. According to the affidavit, the parent of a Lansdale Catholic lacrosse player filed an anonymous complaint accusing Udinski of throwing a player to the ground and hitting another with a stick.

School officials suspended Udinski while they investigated. Ultimately, they deemed the claim unfounded and reinstated him as coach, according to the affidavit from Detective Drew A. Marino.

But conflicts within the team - the court filings refer to a "heated verbal argument" Udinski had with assistant coach Ray Cassel and another with players - led the school not to renew his contract last summer.

Udinski, an officer of regional and statewide lacrosse associations, didn't leave quietly. He allegedly tried to enlist parents to petition for his reinstatement.

"Would we be doing this if this was Algeo?" he argued, according to the affidavit.

He apparently tested that theory in October. That's when the victim assistance office at the archdiocese received an anonymous e-mail complaint that Algeo, the Crusaders' head football coach for 44 years, had solicited sex from a player. The complaint also said school principal Tim Quinn ignored a history of complaints about the longtime football coach.

The archdiocese notified county detectives, who launched an investigation, interviewed players, and ruled the claim a hoax.

Similar e-mails arrived in March, this time targeting the school's new lacrosse coach, Nick Pison. The e-mails, from anonymous Yahoo.com accounts, said Pison had raped students while a fraternity brother at Lehigh University, and demanded that he be removed as a coach at Lansdale Catholic.

Each complaint stirred a new round of questions and interviews by county detectives, but no evidence to support the claims - or identify the sender.

Investigators determined the e-mails were sent through bogus addresses over free Internet service in Bucks County public libraries. But the libraries didn't have surveillance systems or require Internet users to register.

Then two more complaints arrived in May. One accused Pison of sexually abusing a high school lacrosse player; the second said he had tried to lure a minor to the Shore for a sex assault. Like the Algeo complaint, this one said that Quinn, the school principal, knew the coach was a predator.

That last e-mail proved to be Udinski's undoing, prosecutors said. Detectives traced it to a King of Prussia communications company where Udinski worked earlier this year as a salesman.

There, they found proof that Udinski had been using his company-issued laptop computer at the same time each e-mail was sent, the affidavit said. When they confronted him, he allegedly confessed.

"I just wanted to get back at the church, Tim Quinn, and I was just generally mad," he told Marino, the detective's affidavit said.

Udinski was arraigned Tuesday before District Judge Harold Borak and released on $25,000 unsecured bail. He faces a preliminary hearing July 27.

Archdiocese and school officials praised the county investigators for their commitment to solving the case.

Quinn and Lansdale Catholic president Jim Casey said they were relieved the ordeal was finally over.

"It's been difficult on the staff, [and] it's been difficult on the students most especially," Quinn said. "They've been interviewed three times by D.A.'s detectives. I think that's where a majority of the angst was."

Contact John P. Martin at 215-854-4774 or jmartin@phillynews.com, or follow on Twitter @JPMartinInky.