Kateryna Yechenko was a young woman from Eastern Europe brought to the United States as part of a human trafficking ring by "Nachalnik" who is also known as Linda Boyka. In 2005, she escaped when she betrayed another girl Lena Golovnka and murdered an innocent man named Mike Chulaski who'd been trying to help Lena. She was arrested for the murder when the case was reopened two years later.
Little is known of her life before she crossed paths with Mike. She endured a life of forced prostitution, serving as many as ten men a day. She resisted at first, believing someone would save her, but soon gave up such hope. She was also treated at one point for a drug overdose. In 2005, Mike came to 12 Pearl Street (the house where Kateryna, Lena, and other girls where being held), hoping to find and rescue Lena, who had been abducted and brought there by Kiril, one of Boyka's men. Mike bribed Kateryna to take him to the back room were Lena was being kept for resisting.
Mike was unable to walk Lena out as her feet had been burned with a cigarette by Boyka as punishment. Kateryna tried to tell him that he was only making things worse by getting her hopes up and that he could not save her. Mike didn't listen until she warned him Nachalnik was coming. Boyka entered moments later and had her enforcer Yuri drag Mike out.
Mike was later able to make a deal with Boyka to buy Lena's freedom. Mike would make the exchange with Kiril at a motel while he kept Lena in another room with Kateryna watch her.
Lena was clearly excited at escaping her life and living with Mike. Kateryna, who was older, jaded, and perhaps resentful, warned her not to get her hopes up.
Kateryna then answered a phone call meant for Lena. It was Kiril, telling her to stay put that he'd be back in an hour. Kateryna, immediately sensing an opportunity, lied and told Lena that Mike now wanted a girlfriend for sex and had asked for her instead. Leaving the heartbroken and crying Lena, she headed over to the room Mike was in.
She walked in and was told Kiril was going to inspect Mike's boat, which he'd offered to trade for Lena. When Mike asked where Lena was, Kateryan lied again and said she wasn't there, then tried to seduce him. When he rebuffed her, she broke down and begged him to take her instead. Mike was sympathetic but said he only wanted Lena, offering to help Kateryna once he had her. She continued to plead with him but he only apologized.
In a moment of anger and frustration, she picked up a lamp hit Mike over the head with hit repeatedly, killing him. Kateryna stared at Mike's lifeless body for a moment, unsure of what to do next, until her eyes fell on his feet, giving her an idea. She removed his shoes and socks and burned the soles of his feet, hoping to frame Nachalnik for Mike's murder. She then took his boat keys and fled.
Kateryna was able to sell Mike's boat and used the money to start a day spa in the town of Bellport, Long Island. She lived comfortably for two years until Detectives Scotty Valens and Kat Miller walked in and started asking questions about Mike. Kateryna feigned ignorance at first until it became clear to her that they had no idea what happened. She lied when they asked how she got away from Pearl Street, telling them she went on her own and built up a nest egg after she was too old. She willingly gave up Boyka's identity as Nachalnik and told of Mike coming to Pearl Street for Lena, and of Nachalnik's habit of burning feet, making it appear she was Mike's killer.
Kateryna's appeared to have worked until Scotty returned with Detective Will Jeffries. They had questioned Boyka, Kiril, and found Lena, and now knew Kateryna had been at the motel as well. Kateryna defended her actions by reminding them of the life she had endured and no one had ever come for her as Mike had for Lena. Nevertheless, she was arrested, along with Boyka and Kiril.