The e-mail's subject line was "Interested in hiring you." The sender, a woman, said she had seen me on a local Baltimore news show talking about revenge porn, and she was "interested in talking to you about some work." She gave an office phone number, and her e-mail address was from a large local hospital system, so I thought it might be for some sort of speaking engagement.

It was anything but. When I contacted her, the woman told me her life had been turned upside down by her ex-boyfriend. He had hacked her phones, her voicemail, and her family's computer, and he was blocking her out of her digital life. She was looking for someone to help her regain control.

To some, those claims might sound like paranoia. But there are thousands of incidents of this type of abusive use of technology annually, perpetrated by (mostly male) spouses or partners. The most public forms of tech-centered abuse, especially revenge porn, are getting attention from legislators across the US right now. But these incidents are not entirely new. For more than a decade, domestic violence and "intimate partner" stalking and harassment have relied heavily on technology.

The most recent comprehensive study on stalking and domestic violence, conducted by the Department of Justice in 2006, found that more than 887,000 people were aware that they were victims of cyber stalking or electronic monitoring in that year alone. And that was a year before the iPhone was released and well before the smartphone boom really began.

Domestic violence, digital style

The woman who contacted me claimed her ex-boyfriend had put tracking software on her BlackBerry smartphone. When she found the suspicious files on the phone, she tried to delete them—but they reappeared. Then she was locked out of the phone entirely, and her voicemail password was changed. When she switched to a backup phone—a flip phone belonging to her father—she soon found the voicemail password for that number had been changed as well. And when she had a technician check a family computer, it was found to have remote access software and a key logger installed on it.

The alleged stalker was described to me as a 59-year-old man with an IT background. The woman said she had met him when they were both in college and had been re-introduced to him recently by his relatives. She told me that now, she was afraid to even bring another computer for her daughter into her home, because she feared her ex would somehow be able to hack into it.

I told her to contact her cellular carrier and law enforcement. Then I reached out to Verizon to see if they would share any more information about how prevalent cases like these are.

A Verizon spokesperson wouldn't comment, but instead directed me to contact Cindy Southworth, vice president of the National Network to End Domestic Violence (NNEDV). Southworth spends much of her time crossing the country to provide law enforcement training on the use of technology in stalking and domestic violence cases.

"The crimes and the behaviors aren't new," Southworth told me when I reached her between transcontinental flights. "What's new is the tools. If phones weren't important to people, then they wouldn't be such a target. We hear tons of stories about phone and computer misuse."

Some of those stories were detailed by Southworth and other researchers in a 2007 paper documenting the use of technology in violence and stalking of "intimate partners." One 2003 case was the earliest documented use of GPS tracking by a stalker—a Wisconsin man who knew his ex-girlfriend's every move because of a GPS device he planted in her car.

The most comprehensive study, unfortunately, predates the iPhone. That 2006 Department of Justice survey, first published in 2009, found that of the estimated 3.4 million victims of stalking that year, most were being surveilled or harassed by their stalker in multiple ways.

Reported incidents of digital stalking in 2006 Cyber stalking involving e-mail 732,105 Cyber stalking involving spyware 298,166 Cyber stalking involving GPS 96,727 Cyber stalking involving listening devices 370,933 Cyber stalking involving video/digital cameras 410,866 Cyber stalking involving Internet sites about a victim 83,416

There haven't been any substantial surveys performed since 2006, but there have been obvious changes in technology that have made cyber stalking even easier and apparently more prevalent. And there's little that can be done to prevent someone with whom you're in a relationship—especially an abusive one—from using your digital devices against you.

"Think of how many times you leave your phone unattended," Southworth said. "And there's this idea that people get that if you don't share passwords with your best friend or your boyfriend, you don’t trust them." Once someone has physical access and the password, it's difficult to roll that exposure back. Furthermore, the market for spyware and other tracking tools for mobile devices has been growing.

There are even apps, particularly for Android phones, specifically marketed "as 'how to spy on your spouse,'" Southworth said. Apple and Google have tried to keep such tools out of their stores. Apple's vetting process blocks the majority of applications, and Google responds quickly when apps marketed specifically for monitoring are published to the Play store. "As soon as they're reported to Google, they're pulled from the store," Southworth said.

But many times, the tools used by stalkers are ones marketed for "family safety," or even for corporate use, such as mobile device management tools. That was probably the case with the BlackBerry used by the woman who contacted me—just because of the nature of what's available on the BlackBerry platform.

Hacking voicemail, as demonstrated by recent phone hacking scandals in Britain, isn't exactly rocket science. The abuser may just social engineer their way past a phone provider's customer service. "Often the way for an abuser to reset the voicemail password is to know something about the victim," Southworth said.

For that reason, simply changing a hacked voicemail password isn't a guarantee that the problems will stop. "We recommend whenever possible that when people change passwords and pin numbers, they ask for additional passwords to protect their account. Ideally, those should be random. If they need to provide answers to secret questions, they should provide a geographic location instead of a favorite food or any other detail that the abuser could know."

In the case of Verizon, the company can track any password change activity for a cell phone's voicemail and put an additional verbal "entrance" passcode on the account to prevent anyone else from calling customer service. However, when the victim who contacted me called in after putting one in place, she said the customer service representative didn't ask for the new password.

Clearing the case

In this particular case, going to law enforcement wasn't going to be much of an option. The woman said she had gotten rid of the BlackBerry, so there was no way to perform forensics on it to gather evidence. The same was true of her father's computer, which the technician had wiped clean.

That's a common problem in dealing with these sorts of cases, Southworth said. "Some victims just want their device clean and just want the stalking to stop. But if you clean off the device, you're destroying the evidence." And for victims who are trying to deal with an abusive relationship, trying to do anything to remove malware from a phone or computer could put the victim in danger. "Even looking for the spyware can raise the risk," Southworth said, because the software could alert the attacker of the attempt and trigger violence.

And even when software is removed, the persistence of such stalkers usually means that they won't stop their behavior—they'll just take different approaches. That, paradoxically, is an upside for law enforcement, Southworth said. "They don't stop, so if she wants law enforcement to get involved," she said referring to the victim, "there's likely another form of stalking going on for them to catch him with."