Domestic abuse shelters across the country are seeing a disturbing trend: Victims are discovering their partner has installed secret surveillance software on their phones to surreptitiously record their calls and track their location.

The software is cheap and easy to install. A simple Google search reveals dozens of options. A 2016 Government Accountability Office report identified more than 40 apps that can secretly track phone activity. And many of them are marketed to parents who want to track their children.

“What we assume is that everything is tracked,” said Liz Ortenberger, who runs SafeNest, a Las Vegas domestic violence shelter that provides counseling and other services to 45,000 victims a year.

Take “Harper,” for example. She left her husband two years ago and toward the end of their three-decade relationship, she said, he secretly installed software on her phone that tracked her location, read her text messages, and recorded her calls.

VICE News disguised her identity because she's still afraid of her ex-husband.

People who install these apps onto their spouse's phone are typically in violation of three laws: the federal wiretapping statute, the Computer Fraud and Abuse act, and the federal stalking statute.

But prosecution is rare, at least in part because detection is also rare — and difficult.

This segment originally aired September 6, 2018 on VICE News Tonight on HBO.