For more than four years, a sexual predator used Facebook and Twitter to trick teenagers into sending him nude photos and other sexually explicit images.
He maintained more than 50 false aliases, most of them female, and used a variety of cover stories to manipulate his victims, most of them young men.
To some, Anton Alexander Martynenko was a woman who had recently moved to Minnesota and was looking to make friends. To others, he was an employee at a modeling agency looking for new talent.
In each instance, Martynenko slowly began to shift the conversation, eventually convincing each victim to send him nude photos or sexually explicit videos. He then threatened to distribute the photos, sometimes demanding sexual favors, sometimes just sending them to the victim's friends and family on social media.
In January, Martynenko, 33, pleaded guilty to the production, distribution and advertising of child pornography. Last month, he was sentenced to 38 years in prison for the child pornography scheme.
The federal case, the largest example of "sextortion" and production of child pornography to be prosecuted in Minnesota, affected more than 155 victims across three Midwest states.
Although Martynenko had been on the radar of metro area law enforcement agencies since as early as 2013, it wasn't until officer Beth Richtsmeier of the Rosemount Police Department started working with teenage victims in the area that the case finally broke open.
Assistant U.S. Attorney Carol Kayser, one of the prosecutors on the case, said that Richtsmeier was the first person to recognize the scope of the case and follow the digital trail that led to Martynenko.
"Mr. Martynenko's activities had been going on for four years... Beth was the first person who started connecting the dots and realizing that there could be one person behind all of this," said Kayser. "In Rosemount, you had a number of victims who had been being terrorized for years."
'We're going to figure this out'
Anton Martynenko's scheme to exploit teenage athletes came to Richtsmeier's attention in April 2015. Using a decoy Facebook account to conceal his identity, Martynenko contacted an undercover Facebook account maintained by the Rosemount Police Department advertising naked photos of current and former Rosemount High School students.
Within just a few days, a former RHS student sent an email to Richtsmeier and school administrators to tell them about classmates who were being threatened and harassed online over nude photos they'd shared as students. Several current RHS students also approached Richtsmeier individually to report they were being targeted.
"It all just came right together and I thought, 'Well, I don't quite know what this is, but we're going to figure this out,'" Richtsmeier said.
Richtsmeier soon learned that some of the students had filed police reports with other metro agencies over the harassment. These reports included the names of other victims, information on some decoy accounts, and similar stories of how Martynenko would manipulate, exploit and harass victims he connected with.
Each of the investigators "followed the leads where they went, but hit a wall," Richtsmeier said. "As we would find out later, Anton had 50 different (social media) accounts that he would shut down and then start a new one."
Victims play a vital role
From the moment Richtsmeier started working the case in April 2015 until Martynenko was arrested that November, she maintained contact with the victims she spoke to in Rosemount, as well as teenagers and young adults in other areas who were still being harassed.
Very quickly, the case started to consume Richtsmeier's nights and weekends, which she would spend communicating with victims while trying to gather evidence about Martynenko's online activity.
"I would grab some sort of caffeine, coffee or pop, on a Friday or Saturday night and I would wait to look at my work emails because that was my main way of communicating (with the victims)," she said. "All of a sudden my emails would just blow up because my victims would be screenshotting and sharing accounts offering and advertising and distributing (their) photos."
Richtsmeier would respond to each email, letting the victims know what information she needed from each decoy account and trying to calm them down after each new threat. Martynenko often targeted each victim's list of Facebook friends, offering the photos to hundreds of people over the course of several days.
"The victims themselves played a vital role in the investigation because (Martynenko) was so busy with his 50 accounts," Richtsmeier said. "It was a full time job, an obsession of his, there's no way I could have singlehandedly followed all of that."
Dr. Timothy Conboy, assistant principal at Rosemount High School, said Richtsmeier's presence as a school resource officer helped build the foundation for these important relationships.
"She works really hard to create positive relationships so that people trust her, so that if something is happening that they feel comfortable and have someone here to talk to," Conboy said. "I think that's why the investigation was so successful — she's created this culture where people trust her."
Digital forensics and Facebook
By that summer, Richtsmeier felt she had taken the case as far as she could on her own. She was confident Anton Martynenko was the man she was looking for, but wasn't sure what came next — although she'd spent 17 years as a crime scene technician, the work of computer and digital forensics was new to her.
Fortunately, the city of Rosemount is a member of the Dakota County Electronics Task Force, a group organized through the Dakota County Sheriff's Office that provides resources and support for computer forensics to local agencies.
Cities in Dakota County provide personnel or money to the task force, in exchange for assistance on complicated digital forensics cases. For Rosemount, the dollar figure provided to the task was well exceeded by the time and resources invested in supporting the Martynenko investigation, said Detective Ryan Olson of the Dakota County Sheriff's Office.
When members of the task force heard about Richtsmeier's case, they reached out to find out if they could help. Olson said he and another task force member met with Richtsmeier and "broke down the case ... and explored options of doing investigative techniques with Facebook."
Over the next several months of the investigation, Olson said members of the task force invested significant time and resources in the case. One project, recovering data from a cellphone damaged after it was thrown in a toilet, took more than 300 hours. They also helped parse data collected through online search warrants and gather irrefutable evidence from electronics collected at Martynenko's residence.
"When I got that phone call from Dakota County Electronics Task Force I thought, 'Now I'm going to get him because I'm going to be successful, because now I have the experts that can help me and explain to me what I'm looking for,'" Richtsmeier said.
Taking on a federal case
By August, Richtsmeier decided she needed to expand her search. She sent out an email to all law enforcement agencies in Minnesota inviting them to Rosemount for a meeting to share information that might be related to the case.
Around the same time, Richtsmeier's colleagues in Rosemount and Dakota County began to suggest that the case might be big enough to go federal. The investigation had confirmed dozens of victims, and several were from other states like Wisconsin and Illinois.
For Richtsmeier, there were two benefits to potentially pursuing a federal case — additional support for the investigation, and a longer sentence if Martynenko were convicted.
The problem? No one really knew what they would need to do next.
Read the second part of this story here, including the pursuit of a federal case in conjunction with the U.S. Attorney's Office and the Federal Bureau of Investigation, executing a search warrant at Martynenko's residence in Eagan, and finally making an arrest in the case.