A substitute teacher in Minnesota has pleaded guilty to charges of child porn and extortion after he blackmailed teenagers into sharing sexually explicit images of themselves.

James Ottinger, 25, from the city of Carver in the US state of Minnesota, has pleaded guilty “to child pornography and extortion charges related to a years-long sextortion scheme”, the US Attorney’s office for the District of Minnesota announced in a statement on Tuesday 19th October.

The court documents pertaining to the complaint against the teacher alleged that he “engaged in a scheme to obtain sexually explicit images and videos of minors and adults by using false online personas”.

The documents also reveal one image described as a screenshot from a mobile phone showing messages sent between the defendant and one victim.

The identities of the teacher’s victims have not been revealed in order to protect their identities.

According to the complaint, the image shows one of the defendant’s victims, whose name was redacted from the document as they were only 15 years old at the time, without any clothes on.

The image has been greyed out by the authorities but they said that the unaltered version of it shows the teen boy fully naked in front of a mirror.

The teacher sent the image back to the victim with the message: “Gunna show all my friends unless ur a good boy.” (sic)

The victim replied: “This is literally blackmail.”

The statement from the District Attorney’s Office confirmed that “Ottinger threatened to disseminate the images and videos of his victims in order to extort more images and videos.”

Ottinger was accused of having victimised over 10 minors “over the course of several years”, and he knew some of his victims “from the school district where he worked”.

The authorities began investigating the teacher after one of his victims “contacted the FBI’s National Threat Operations Center and reported the threats”.

The authorities said there could be “additional victims” who have yet to come forward, “based on the evidence obtained in this investigation”.

The statement said that Ottinger pleaded guilty before Judge Wilhelmina M. Wright to “two counts of production and attempted production of child pornography” and to one count of “interstate communication with intent to extort”.

The statement also said that a sentencing date has yet to be scheduled and that the investigation and resulting charges were the “result of investigations conducted by the FBI and the Carver County Sheriff’s Office”.