Late last month, police in Chaska, Minn. obtained a search warrant after a Twin Cities woman reported finding tracking devices in her vehicle following a judge granting an order for protection against her former boyfriend, a South Dakota man.

In a search warrant application, police describe the woman becoming suspicious after being alerted to the man having an audio recording of a conversation she had with her attorney after a child custody hearing, and him being aware of details he shouldn’t have known. After searching her car with a friend, she found a cell phone wrapped in a children’s sock hidden in a compartment of her vehicle.

She told police that four months prior, the man was making a repair to her car, and “[at] that time, she had found plastic pieces inside her car that she found odd.” A hole was drilled with wires leading to a 12-volt power line so the device could maintain a constant charge, the search warrant application said. A recent local newspaper article stated the man has a background in custom fabricating, and an online business directory associates him with an electrical contracting company.

That wasn’t the only tracking device in the vehicle: she also discovered that what appeared to be a standard USB car charger for her phone was actually a GPS tracker with a cellular SIM card inside.

Advertised as a “spy device” and available online for about ten dollars, the car charger can be commanded remotely via text message to send GPS coordinates and record audio files to a memory card. One version of the device sold online includes the capability of sending voice-activated audio recordings via text multimedia message (MMS). The device, memory card, and SIM card are in the hands of police, who describe in court filings that “on one of the control boards there is a section labeled ‘MIC’ with positive and negative terminals that are wired to a small round microphone looking device.”

Stalking allegations against the man go back years, according to Day County, South Dakota prosecutor Danny Smeins. “He was doing something like connecting to her car, and [he] would unlock and lock the doors [remotely],” he recalled of a prior situation, “He had also given their son something, and it was actually…some sort of surveillance device.”

Chaska Police said in a court filing that the man spoofed his caller ID so that his calls to the woman would appear as other people in her contact list, to get her to answer his calls. Court documents allege the man forged text messages to make it falsely appear the woman made statements that she didn’t want custody of their child.

“We suspected he cloned a phone because it looked like there was a threatening message from the woman in Minnesota…threatening him…but he had enough technological savvy to somehow clone her phone to make it look like it came from her phone,” Smeins said, going on to describe how the man also falsely accused the woman of trying to run him over. She was jailed and charged with aggravated assault in a neighboring county, but “there was a witness,” Smeins said, “It was all made up.” The woman said it took a year to clear her name and get the charges dismissed.

A Facebook account with the same name and phone number as the man ‘likes’ a service called FakeMySMS, which has an advertisement on its homepage suggesting that its service can be used to break couples up by sending fake ‘spoofed’ text messages. According to screenshots submitted to the court, a YouTube account under the same name as the man had added a video titled “How To Track The GPS Location Of Any Cell Phone” to his favorites list.

Reached for comment, the man said he had received a copy of the order for protection documents—which included allegations about GPS tracking—but that he didn’t bother reading it. Asked directly if the GPS tracker came from him, he respon“I don’t know.”

On August 22, a judge granted a warrant to search the contents of the hidden cell phone, as well as the SIM card and memory card in the car charger. Police would not comment on the active investigation, but told the court they “believe that information on the phone, SIM card and microSD card may leave a digital trail to assist [investigators] in locating what kind of software is being used to track [the woman] and who is doing such tracking.”

Criminal charges have not yet been filed, so the man is not named here, but investigators said they are handling the matter as a criminal stalking case and being assisted by the Carver County Sheriff’s Office.

South Dakota court records show six others—four women and two men—had applied for stalking or domestic abuse restraining orders against the man from 2011 to 2017. All but one of those orders for protection were granted.

Court records also indicated the man was charged with domestic abuse in 2013—which resulted in a deferred prosecution—and in 2015 with stalking, which was reduced to a disorderly conduct conviction with a $350 fine. He did not have to report to jail for a 30 day sentence as long as he maintained “good behavior” for six months. This morning, the man was arrested in Day County, South Dakota on an unrelated assault charge, which was said to involve threatening text messages to yet another individual. According to the Day County Sheriff, he made an in-custody court appearance and his bail was modified to a release on his own recognizance.

The National Domestic Violence Hotline, 1-800-799-7233, has resources to help anyone experiencing domestic violence. If you think you’re being monitored, use another phone or computer to reach out for help. If you’re in immediate danger, call 911. The National Center for Victims of Crime maintains a Stalking Resource Center with information to help victim service providers understand how technology can be used by stalkers.

This story has been updated to reflect the new custody status of the defendant in the unrelated assault case, and to add comment from the defendant and prosecutor.