Tim Udinski was livid.

Just a year after becoming the head lacrosse coach at Lansdale Catholic High School, he was out, ostensibly because of heated arguments with players and an assistant.

Udinski thought the decision unfair, one the school wouldn't have considered for someone like longtime football coach Jim Algeo. So last fall he launched a scheme to prove his point, authorities say.

Udinski sent anonymous emails to the Archdiocese of Philadelphia, first claiming Algeo sexually solicited a player, and then accusing the new lacrosse coach, Nick Pison, of sexually assaulting students, officials said.

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

District Attorney Risa Vetri Ferman said his offenses were particularly galling because he tried to take advantage of a national spotlight on child-sex abuse to destroy reputations.

"The current publicity, it raises awareness and that is a wonderful thing," said Ferman. "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, a 43-year-old Doylestown resident with years of service in youth lacrosse leagues across the region, confessed when confronted last month, according to an affidavit filed in the case.

"I was mad at the school for the way I was treated. I was just furious," he told county detectives, the filing said.

Detectives spent more than 150 hours interviewing Lansdale Catholic students and staff and chasing the false sex-abuse complaints.

Udinski was arraigned today before District Judge Harold Borak and released under $25,000 unsecured bail. Reached by phone after his hearing, he declined to comment.

Udinski himself had been the target of a similar smear campaign last year, prosecutors said.

In March 2011, the archdiocese received two anonymous complaints sent from the email address protecttheboysatlc@yahoo.com. The emails accused Udinski of inappropriately touching one player, throwing another to the ground and hitting a third with a lacrosse stick.

School officials suspended Udinski while they investigated. They tracked the emails to a parent of a player, determined they were false and reinstated Udinski as coach.

But his contact was not renewed last summer.

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