Transcript for Florida lawyer arrested for allegedly putting a GPS tracker on ex-girlfriend's car

Back now with Florida lawyer arrested this month, accused of stalking an ex-girlfriend by putting a a gps tracker on her car. Several recent similar cases. Here's ABC's Marci Gonzalez and why it's happen something often. Reporter: Tonight, authorities in Miami say it was a magnetic gps tracking device like this that helped grant sarbinoff stalk his ex-girlfriend. He's accused of secretly attaching it to her vehicle, using to remotely monitor her every move. And more cases like this making headlines across the country. Slapping on a tracking device is as easy as finding the metal piece that is under the vehicle, slapping on the tracking device and you walk right away. Reporter: The devices, once only used by law enforcement and private investigators, are now alarmingly accessible, selling online for less than $0100. And they are virtually undetectable. It could be attached and you have no idea. It requires physical inspection. Reporter: The attorney for sarbinoff's alleged victim says she became suspicious only after sarbinoff started inexplicably showing up where she was. He's pleaded not guilty to charges including stalking. When you start to see that level of commitment and sophistication to a criminal, you know, deviant course of conduct, it's really alarming. Reporter: Experts say if you suspect you're being stalked, bring your vehicle to a rep table shop. Marci, thanks so much. Still ahead -- health

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