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For at least four years, aliases like "Marie" and "Courtney" prowled around social media, claiming at times to be a college student new to Minnesota and a nude model at others, collecting sexually explicit images from high-school-aged boys.

Authorities on Friday arrested an Eagan man they say was behind the accounts and accused him of storing and trying to share nude images of the victims. Anton Martynenko, 32, was charged in U.S. District Court in St. Paul with production, advertising, receipt and possession of child pornography.

According to the charges, federal investigators began looking into Martynenko this summer after several local law enforcement agencies reported similar stories from high school male victims. The victims said a person claiming to be a female contacted them on social media, convinced them to send naked pictures of themselves and threatened to distribute the photos if they didn't send more. In some cases, the criminal complaint said, the photos were sent to victims' classmates.

Investigators searched Martynenko's home on Oct. 2, seizing flash drives, a tablet computer and other electronic items found hidden above ceiling tiles. They also found a damaged laptop computer hidden in a laundry room that they believe Martynenko tried to destroy.

A partial forensic review of the devices revealed thousands of nude images of teenagers and young men, many sorted by folders labeled with their names, ages and hometowns. According to the charges, the search totaled more than 300 victims from Minnesota, Wisconsin and Illinois.

A separate cache of photos contained "decoy" images authorities say Martynenko used to pass himself off as a young woman on social media.

One victim said that a person with a female profile named "Marie Anna" messaged him on Twitter and later tweeted naked photos of him that were tagged with his name. After the victim reported the activity to Twitter, he said the posts later continued from a different profile.

Young people cautioned

U.S. Attorney Andrew Luger in a news release urged teenagers and young adults to be "particularly cautious and highly skeptical" of strangers online.

"Unfortunately, there are far too many people who seek to take advantage of and harm our youth over the Internet," Luger said.

In April, investigators opened an undercover Facebook account posing as a 24-year-old woman who graduated from the same high school as one of the victims. "Marie Anna" messaged the account and offered nude photos of a "minor boy." Authorities say Marie Anna's profile photo was included in a folder of "decoy photos" found on one of Martynenko's flash drives.

According to the charges, investigators also discovered videos of males changing in a locker room; Martynenko's head could be seen in some of the camera angles.

Martynenko will appear in court on Wednesday for a detention/preliminary hearing. U.S. Magistrate Judge Janie Mayeron ordered Monday that he remain held until then.

Stephen Montemayor • 952-746-3282