Columbia, SC (WLTX) -Whenever you talk or text, your cell phone is repeatedly sending it's serial number to nearby cell phone towers, giving cell providers your trail.
Across the United States, and in Richland County, law enforcement can gather vast nets of data from those cell phone towers, without notifying the individual subscribers even if they're not related to the investigation.
"This entire phenomenon is shrouded in secrecy," said Christopher Soghoian of the ACLU. "The vast majority of people whose information is being collected are innocent of any crime. They're never told their information was requested and they're never told their information ended up in a government database."
An investigation by USA Today and Gannett TV stations reveals the feds and at least 25 local police agencies use a method called 'tower dumps' to collect cellular data.
As we reported several weeks ago, it's happening in Richland County.
Deputies used tower dumps during their investigation into the 2005 murder of Gadsden store owner Freddie Hill.
They used tower dumps at least one more time. Phillip Tate, who pled guilty last month, stole a gun from Richland County Sheriff Leon Lott's car. It happened during a string of car break ins, where search warrants we found show tower dumps helped deputies catch the crook.
"We would be derelict in our duty if we didn't," Lott said. "We are not infringing on their rights. When they use that telephone. they understand that information is going to go to a tower. we are not taking that information and using it for any means whatsoever, unless they're the bad guy."
Cell phone companies will hand over your data as long as police have a court order or search warrant according to Counterterrorism consultant Keith Pounds. "In recognizing that it's not just the CIA or FBI tracking a terrorist that may have flown over here, this is local law enforcement. And as citizens, we sort of have a question: how often is this happening?"
In 2011 alone, two top providers, AT&T and Verizon, filled more than half a million requests for your data. But if you're not the bad guy, laws don't outline what should be done once police do a tower dump and have your records.
"We have no ability to know what the government is doing and that is problematic," says Denise Maes of the ACLU in Colorado.
Most privacy experts agree that lawmakers and the courts will have to soon decide what's needed for police to get a tower dump and what they must do with the data once an investigation is complete.
Right now, most cell providers require law enforcement to have a court order or search warrant before cell data is released.
"Americans deserve a reasonable expectation of privacy," said Rep. Dennis Ross, R-Florida. "It's something we need to be concerned about because more and more I think we're seeing an invasion of what we would expect to be a private part of our lives."