Stingray technology has been used for some years for tracking phones within the range of the device. It was developed during the Iraq War to try and find cell phones used in IED attacks. Harris Corp. developed the tech.
In one case where a local PD used it in NY State, they went to a specific residence to look for a suspect, but they had no idea if he was there, so they tried to track a phone linked to him. When the Stingray device is close enough it can track a cell phone's location to within 6 feet. When the information about the arrest and its circumstances came up in the trial, the PD's officer who was in charge of the apprehension was asked how they knew the guy was in the house. The PO clammed up and wouldn't elaborate.
Reason being, the PD should have gotten a warrant before trying to apprehend the suspect, but they didn't. There's also the issue of privacy and the Constitutionality of how the Stingray was used. Stingray can be either A) Mobile, say in a van, or B) Stationary, placed on a pole/mast of some sort or another. Bottom line, they should have a warrant to track a specific cell phone, which includes the stationary Stingrays. LE use the stationary ones to get all nearby cell traffic, commonly used in tracking drug dealers, things of that nature. They should still have to get a warrant to then track a specific phone picked up by the stationary Stingray.
Hope this helps clear things up, sometimes the media don't explain much about how such tech is used.
It's very expensive, often times used only in specific investigations by local and state police departments
.
Let's say LE have a cell phone or cell phones in the Delphi case they think may be linked to it. If they fingered a suspect, they could put a Stingray near the suspect's residence, workplace, etc. If LE determines there's a link between, say, Bridge Guy with cell phone traffic picked up by the Stingray by phone numbers or other phone data, say a SIM card switched to another phone, that type of thing, then they could request a warrant from that county's court.
Stingray can also mimic a cell tower:
Stingray phone tracker - Wikipedia
-FD