An 18-year-old North Oaks man was charged Monday with coercing two girls — one 12 and the other 13 — into performing a sex act after meeting one of them online and persuading her to make a sexually explicit video.

The Ramsey County attorney's office charged Alexander Patrick Lindeke, a recent Minnesota National Guard recruit, with two counts of criminal sexual conduct — one in the first degree and one in the third degree. Prosecutors say he coerced the girls by threatening to post the video online.

Lindeke was arrested May 29 in the parking lot at White Bear Lake High School in "the vehicle which he had driven to school that day," the complaint said. A spokeswoman for the White Bear Lake Schools said he transferred to the high school in December 2014 from a private school in St. Paul.

According to the complaint:

On May 27, the Ramsey County Sheriff's Office took a report from a 12-year-old girl and her parents stating that three days earlier, the girl made a sexually explicit video of herself. She did this, she said, at the request of Lindeke, whom she met online at a website called hotornot.com. She transmitted the video to Lindeke.

The next day, she said, she and a 13-year-old female friend met Lindeke at Cummings Park in Arden Hills after Lindeke threatened to publish the video. The two performed a sex act on him in his vehicle, according to the complaint.

Investigators say the friend corroborated the 12-year-old's account. Both girls identified Lindeke from photographs, according to the complaint.

If convicted of first-degree criminal sexual conduct, Lindeke faces up to 30 years in prison. The third-degree charge carries a maximum sentence of 15 years.

According to the complaint, Lindeke also is under investigation by the North Branch Police Department in a similar case involving another girl he allegedly met online.

A spokesman for the Minnesota National Guard released a statement Monday, saying in part that Lindeke "enlisted in the Minnesota National Guard on 29 December 2014 and was scheduled to attend basic training in August."

Lindeke's Facebook page — the one that one of the alleged victims said he uses — shows a photograph of him being sworn in as a member of the Guard. "I'll be becoming a geospatial engineer now. Wish me luck everybody!" he wrote in December.

James Walsh • 651-925-5041