The text message came from a person calling himself “Sycamore Neighbor”: “When sneaking around at night and switching and hiding vehicles, please remember to shut the lights off in your house so you don’t waste electricity.”

The message’s recipient, an Irondequoit, New York, woman who lived off a Sycamore Street, had already changed her phone number and traded in her car her car after months of threats. But the text was the latest indication that someone was watching her more closely than ever.

On Thursday, the FBI arrested William Rosica, an Irondequoit police officer, for allegedly harassing and cyberstalking the woman, his ex-girlfriend, for a year. Rosica, 50, allegedly sent her hundreds of messages from fake email addresses, attempted to hack her medical records and her employer’s email, photographed her as she traveled, and sent her tutorials on how to commit suicide, after he pledged that “short of killing you, I destroy every aspect of your life.”

Worse still, Rosica was allegedly involved in a near-identical case against another woman less than a decade earlier, prosecutors say.

The latest campaign of harassment began with a breakup, a federal court alleges. In a March 1 complaint, the U.S. District Court for the Western District of New York identifies the victim only as “L.M.,” a lawyer whom Rosica dated until early 2016, when L.M. broke off the relationship. That’s when the text messages began, the complaint alleges.

In March, shortly after the breakup, L.M. received a series of messages from email addresses she had never seen before, according to the complaint. “I have already provided him with all the information he needs to know how you played him,” read one. “And you wonder why you have no friends?” The message was signed from “trustmeiknow@yahoo.com”. Later that day, L.M. received a message from the email address “anonymous,” the complaint alleges. “I think he knows how you played him,” the message warned.

The messages continued, often from what appeared to be fake email addresses from third-party texting services, the complaint alleges. Soon, Rosica allegedly emailed L.M. to complain that he had been receiving the messages, too. “Whatever you do do not trust her she is lying bigtime you fool,” read one of the messages Rosica allegedly said he received. “[S]he needs to tell you something soon she is hiding from you run!!”

The cryptic messages all appeared to accuse L.M. of harboring a dangerous secret. Rosica allegedly took screenshots and sent them to L.M., accusing her of knowing who was behind them and asking her to make them stop.

L.M. agreed to meet Rosica at a park to speak in person, according to the complaint. There, he delivered a chilling ultimatum, the complaint alleges. “I am at a cross-roads,” Rosica told her, according to the complaint. “Either I let you walk away and we lead our separate lives or short of killing you, I destroy every aspect of your life. You tell me what I should do.”

L.M. told him she wanted to walk away and move on, according to the complaint. But a week later, Rosica was allegedly still weighing his options. “With regard to our last conversation in the park, I still remain at a cross-roads,” he allegedly emailed her. “I must protect my better interests.”

It was late August. The next week, the hacking attempts allegedly began. L.M.’s phone carrier began alerting her of unusual login attempts. The following day, Rosica allegedly contacted her complaining that he, too was being hacked, by a person who claimed to know L.M.’s secrets, and where she traveled. “This is all legitimate and NOT bullcrap!” Rosica allegedly emailed L.M., warning her that the emails “could also drag you into this.”

L.M. had had enough, according to the complaint. She changed her phone number and traded in her car for a different model. But the phone hacking notifications continued. And soon someone was taking pictures of her new car.

After L.M. visited her ex-husband one September day, her ex-husband began receiving text messages from “Katy,” one of the aliases that had allegedly contacted Rosica. “I will make sure Bill knows [L.M.] is at your house right now,” one of the messages read, referring to Rosica. “Tell [L.M.] Katy is sending Bill a picture of her car in your driveway while she helps you with yard work.”

Later that day, Rosica allegedly forwarded L.M. a message he said he’d received from Katy. In it was a picture of L.M.’s car in her ex-husband’s driveway. It described what L.M. had been wearing that day. “You are pathetic, PSYCHO, a LIAR, and the MOST untrustworthy person I have ever met,” Rosica allegedly wrote in the forwarded email from Katy.

More emails followed, according to the complaint. In October, “Sycamore Neighbor” emailed L.M. about her comings and goings on the block, telling her to turn her lights off. Two days later a message from a different email address referenced the way she traveled home. “Winton or Monroe tonight?” the person wrote, referencing two local roads. “Watch your speed.”

Then the emails began suggesting suicide, the complaint alleges. A person with the email name “Lights Out on Sycamore” sent L.M. a tutorial on the “7 easiest and best ways to commit suicide.” At least two other tutorials followed. By this point, in mid-October, the messages were coming multiple times a day, according to the complaint. “Watching the movie ‘me before you’ twice in one week is a good sign your thinking of killing yourself again good for you do it right this time psycho,” the sender wrote, implying that he knew what movies L.M. watched and when.

The hacking attempts also allegedly exploded in volume late in the year. L.M.’s phone provider warned her of unusual login attempts on her new number, while the law firm where she worked reported attacks on its computers. L.M. received a notification from a local hospital’s medical database asking if she had recently tried resetting the password to her medical files. She had not.

A local Walgreens called L.M. about a prescription she had long since canceled. “Bout time you picked up youre psyche pills,” one of the now-familiar email addresses allegedly wrote her when she picked up the pills from the pharmacy. Walgreens staff later told the FBI that they received at least 24 calls from someone asking about L.M.’s prescription from late September to early January. In one of the later calls, the caller allegedly impersonated L.M.’s doctor but hung up when a pharmacist pressed them for details.

Meanwhile, someone began emailing L.M.’s supervisors at her law firm, the complaint alleges. “Hey skank tell them the truth and they won’t feel so sorry for you tell them the nasty things you have said about them the other girls at the other firms know the same stuff we do you are a filthy lying skank,” read a January message, one in a litany of emails on which L.M.’s employers were cc’ed.

All this time, Rosica had been employed as a police officer. L.M. told FBI officials that Rosica had boasted of installing an identity-hiding software on his laptop while they were dating. But in late January, the FBI found a way around Rosica’s security measures.

Rosica allegedly used ToR, an internet anonymity service, to conceal his online activities. But the FBI says it tied him to some of the most persistent email addresses, after agents emailed those accounts with a fictitious cease-and-desist letter that required the reader to click a link to view the whole document. The FBI configured the link to land on a page that only opened if accessed by Rosica’s home IP address. When Rosica attempted to click the link in ToR, he received an error message telling him the page was not available for ToR users. So he allegedly exited the secure network and opened the FBI link from his home IP address, apparently revealing his connection to the harassing messages. The FBI also mounted cameras around L.M.’s home, where agents allegedly spotted Rosica’s truck making repeated trips through L.M.’s neighborhood.

Rosica was arrested on Thursday on stalking charges, with a maximum penalty of five years in prison and a $250,000 fine.

Since his arrest, another alleged victim has come forward claiming a similar campaign of harassment in 2009, in what an assistant U.S. attorney described as a “carbon copy” of L.M.’s experience. During a Friday court appearance, Assistant U.S. Attorney Melissa Marangola said she learned of the new allegations against Rosica after a former police officer came forward to relate the previous allegations. The victim had not pursued charges against Rosica because he was a police officer and she feared retaliation, Marangola said.

Neither the Irondequoit Police Department nor Rosica’s lawyer responded to requests for comment on Sunday. Rosica has been denied bail after a judge ruled that “no condition or combination of conditions will reasonably assure the safety of any other person and the community.” The Irondequoit Police Department has placed him on unpaid administrative leave pending the results of his trial.

In court, Marangola referenced Rosica’s alleged promise to L.M. that “short of killing you, I destroy every aspect of your life.”

“He absolutely followed through,” Marangola said. “He attempted to destroy every aspect of this woman’s life. And, he did, both emotionally and psychologically.”