UNDER WATCH

The police "spy plane" experiment is over, but the growing surveillance of Baltimore continues.

- J.Cavanaugh Simpson

DEBORAH KATZ LEVI , head of the Baltimore City Public Defender Special Litigation Section, knew something did not square. One of her clients, Kerron Andrews, had been charged with attempted murder after he was picked from a photo array of possible suspects following the drug-related shooting of three people in Southwest Baltimore in late April 2014. The Baltimore police subsequently issued an arrest warrant for Andrews and, three days later, found him inside an apartment, which wasn’t his home, just west of Leakin Park. Andrews just didn’t see how the police knew where he was. “Something kept happening to his phone, his phone kept dying,” Levi recalls. She sensed the police or state prosecutors had not disclosed everything in the case. Turns out, she was right.

Baltimore police had secretly deployed an active cell-site simulator, frequently referred to as a stingray, which masquerades as a legitimate cellphone tower and tricks mobile phones within a certain radius into connecting to the briefcase-sized device. The cellsite simulator BPD used had forced Andrews’ phone into transmitting signals that enabled police to locate its precise whereabouts. This part is critical: The simulator doesn't wait for outgoing calls to be made. It actively transmits a signal that travels through walls and reaches into cellphones to conduct a general search of cellphones within the device’s radius.