ST. PAUL, Minn. - A former St. Paul school custodian already charged with looking under a bathroom stall at an 11-year-old boy is facing seven more sets of charges for sexually abusing children and inappropriate behavior after new victims came forward.

KARE 11's news partner Minnesota Public Radio News says Walter Johann Happel, 62, of Newport, is scheduled to appear in Ramsey County Court Wednesday. Happel worked at Linwood Monroe Arts Plus school until he was put on administrative leave in February. Happel was charged Tuesday in Ramsey County District Court with seven counts of criminal sexual conduct for incidents where he allegedly sexually abused or had inappropriate interactions with children over a period of more than three decades. He's also facing six new counts of interference of privacy for incidents where he allegedly spied on or otherwise acted inappropriately with boys at the school.

Among those who have come forward to say that they are victims are a close female relative and his son's childhood friend.

School officials were notified of Happel's inappropriate behavior around students numerous times over the years, according to the criminal complaints. In late 2011, a student's mother, who the complaint refers to as AB, spoke to a school social worker after Happel allegedly exposed his genitals to the boy in the bathroom and made a crude comment.

"The woman AB spoke with indicated that the school employee involved in the allegation had been there forever and wouldn't hurt anyone. AB later called the school and spoke with a woman about the incident, but she never got a return call from anyone with the school," according to the complaint. Police spoke to both the school's principal and assistant principal about the incident in early January 2012.

In February 2012, the St. Paul School District issued a written reprimand to Happel after a parent complained that he was giving some boys candy.

"In the reprimand, Happel was directed to use staff bathrooms for his personal use and that student bathrooms must be empty before he could enter. Once he entered the empty bathroom, Happel was instructed to close it off so students could not enter it. Happel was admonished not to give students candy and it was noted that he had previously been so warned," according to the complaint.

The reprimand also mentioned another incident in January 2012 where Happel "lightly slapped a student's behind" and said "I told you I was going to do that if you sagged your pants." That incident was never reported to the St. Paul Police Department, despite the fact that it occurred shortly after AB complained about Happel's behavior with her son.

St. Paul Public Schools released a statement on the new charges, saying that "because of the timing of this new information, as well as a high-energy school board meeting tonight, there was no one available to review the charges, or respond to questions from the media." The district statement says staff will review the charges in the coming days to explore whether officials make a response.

Ramsey County Attorney John Choi thanked the victims for coming forward.

"This is not an easy thing to do and we want them to know we stand by them," Choi said in a statement. "He has preyed on the innocence of children for over 30 years, and I am relieved that we can seek to hold him accountable for these crimes and get him away from our children."

Happel is in custody in Ramsey County and will make his first court appearance on Wednesday.