Aaron Harper, who resigned for undisclosed reasons last week as principal of East Ridge High School in Woodbury, is under investigation for allegedly misusing school district money and resources, police say.

The Woodbury Police Department has opened an investigation into Harper for alleged public misconduct after officials from the South Washington County School District reported the allegation earlier this week, police Cmdr. Steve Wills said Friday.

"We're very early into the investigation, we're just really beginning," said Wills, who declined to discuss details of the allegation. Wills confirmed that Harper was the focus of the probe, but had not yet been ­interviewed.

Harper, the only principal East Ridge has had since the school opened in 2009, resigned abruptly on Nov. 6. School Superintendent Keith Jacobus said Harper's decision followed an investigation into a complaint the school district had received.

Because Harper was not disciplined, nor was any payment made to him to obtain the resignation, the school district did not disclose the nature of the allegations, according to district spokeswoman Barbara Brown. Citing data privacy restrictions, Brown declined to elaborate on the complaint filed by the school district with police.

East Ridge High School is the newest school in the district, and Harper had a hand in its planning before it opened. The school district includes Woodbury, Cottage Grove, Newport, St. Paul Park and Afton and Denmark ­townships.

Harper had previously been principal of Oltman Middle School in St. Paul Park. Before that, he was an assistant principal, administrative assistant/dean of students, science teacher, coach and African-American mentor while working in the Bloomington, Mounds View and St. Paul school districts.

The South Washington County School District plans to retain an interim principal for the rest of the school year and will start a national search for a replacement in January. Mike Johnson, an assistant superintendent, is helping with East Ridge administration until an interim principal is named.

Jim Anderson • 651-925-5039 Twitter: @StribJAnderson