A small tracking device has become an increasingly useful tool in criminal investigations, says the Cleveland Plain Dealer. Global positioning system chips – built into cell phones – allow authorities to track criminals and people in need of help. Cell phones have become important in criminal investigations as people rely more on the phones for conducting business, whether legal or illegal. The technology played a key role in the investigation of the slaying of a doctor on the Ohio Turnpike and the convictions of his wife and her lover in the killing.
Every time a cell phone is turned on, it sends a registration message, including the serial and phone numbers, to the closest cellular tower. A tower receives signals from cell phones on all sides of it. The tower divides the area around it into three equal sectors. A GPS locator pinpoints the sector where the phone is. More than 195,000 towers dot the U.S. landscape. A phone sends updates to towers every few minutes as long as the phone is turned on. That capability helps find people who are lost or missing. Cell phone users make about 240,000 calls a day to 911.