Wis. (WFRV) — The former wife of convicted sex offender Ryan Zellner released a letter stating that she tried to warn authorities years ago but no one listened.Elizabeth Zimmerman made the claim in a letter to court officials. She hopes to read it before the court when Zellner learns his punishment in May for having sexual relationships with several students.Zimmerman writes, “I did my part to stop what Ryan was doing with teenage girls at the time. When the ‘investigation’ began, those who had the power such as the school officials at Southwest High, and those involved in the ‘investigation’ to put a swift end to Ryan’s destructive behavior and to prevent all that would happen to the victims in Kiel, failed miserably.”Zellner most recently worked at Kiel High School, but before that he was employed for a short time in both West De Pere and Green Bay schools.Zellner did reach a plea agreement earlier this year. He faces no more than 25 years in prison when he is sentenced this spring.