Cell tower records can pinpoint a phone owner's location for police, whether the phone is used or not.
By CHRIS TISCH, Times Staff Writer
Published September 17, 2005
A number of Tampa Bay area killers have tried to commit the perfect murder, but they have been caught because of one simple fact.
Today, even murderers carry cell phones.
They may have left no witnesses, fingerprints or DNA. But if a murderer makes calls on a cell phone around the time of the crime (and they often do), they leave behind a trail of records that show not only who they called and at what time, but where they were when the call was made.
The cell phone records, which document what tower a caller was nearest when he dialed, can put a suspect at the scene of the crime with as much accuracy as an eyewitness. In urban areas crowded with cell towers, the records can pinpoint someone's location within a few blocks.
Should a suspect tell detectives he was in another part of town the night of the murder, records from cell phone towers can smash his alibi, giving detectives leverage in an interview.
"It's a very good tool," said Pinellas sheriff's Detective Michael Bailey, who used cell phone tower records to link four men to a murder in Seminole two years ago. "We got them within half a block. I couldn't believe how on-the-money it was."
Investigators increasingly rely on the cell tower records. The Pinellas Sheriff's Office's homicide unit - like many murder squads nationwide - seeks them in virtually every case.
Tower records have been used in several high-profile national cases, including the California murder investigation of Scott Peterson. The records showed Peterson lied to police and relatives about his whereabouts. He was convicted and sentenced to death for murdering his wife and unborn child.
Locally, the records have proved useful in several high-profile cases, including the recent prosecution and conviction of William Deparvine, charged with killing Tierra Verde residents Richard and Karla Van Dusen in Hillsborough County. Deparvine also was sentenced to death row.
Cell tower records also led to the arrests of Timothy and Ashley Humphrey, who are charged in the Pinellas Park murder of Timothy Humphrey's ex-girlfriend in 2003. That case is awaiting trial.
"It's a sure bet that almost everybody is going to be carrying a cell phone," said Bruce Bartlett, the chief assistant in the Pinellas-Pasco State Attorney's Office. "It's just incredible, the information that it gives you."
Nationwide, more than 182-million people have cell phones, more than five times as many as 10 years ago. There are about 175,000 cell sites or towers nationwide, nearly eight times as many as in 1995.
"The more law enforcement has understood this information exists, the more they ask for it," said Al Gidari, a Seattle lawyer who represents wireless companies in complying with court orders.
In 1994, Congress enacted a law requiring police to get subpoenas or court orders for wireless information, and ordering cell phone companies to comply with the court orders.
Gidari said the nation's top five wireless companies receive up to 4,500 requests per month from law enforcement. They receive so many requests that they each have departments with as many as 40 employees to comply with all the requests.
Attorneys in civil, divorce and child custody cases also can get court orders for cell tower records, with which wireless companies must comply. It's pretty infrequent, Gidari said.
Scott Schiltz, a Dunedin lawyer who specializes in family law cases, said he hasn't heard of a local case in which the technology has been used, but added: "I guarantee you if it hasn't, it will."
As for criminal investigations, cell tower technology was first used in the Tampa Bay area in the early 1990s. Tower records helped prosecutors convict Oba Chandler in 1994 of murdering an Ohio woman and her two daughters in 1989; they also were used in 1994 to solve the murder of a St. Petersburg doctor.
Today, cell tower records aren't just used in murder investigations. They are becoming so common that police investigating other crimes - robberies, sex crimes, hit-and-runs - are seeking them, too.
Gidari said wireless companies work hard to comply with the requests in a timely basis. Bartlett said some companies have responded very fast, others too slow.
"Sometimes they don't appreciate the gravity of the situation," he said.
Speed can be an issue if a suspect is a flight risk or someone is in danger - a kidnapped child, for instance. In those cases, the law allows police to circumvent a court order, Gidari said.
In those cases, the suspect doesn't even need to be making calls. If he has his cell phone with him, the phone silently checks in every so often with the closest towers. This is called "pinging."
Those records are stored for only a short time - usually no more than a day - before they are overwritten. If detectives can get those records, it can help them trace a suspect.
Pinellas investigators used that technology two years ago to track a murder suspect to the east coast of Florida. Police eventually found the man, but the suspect shot himself to death before he could be taken into custody.
Law enforcement's use of the records isn't something cell phone companies particularly like to discuss. Nor do police, who say suspects sometimes unknowingly set a trap for themselves by using cell phones when they commit a crime.
But investigators figure the cat is out of the bag. They also are getting better at using it.
"The criminal community has proved to be an early adopter of our industry's products," said Rick Kemper, director of technology for CTIA-The Wireless Association, a trade agency that represents wireless companies. "They (police) seem to be getting more savvy about how the network works."
For instance, the records can show how a suspect moved at the time a crime was committed. Cell phone towers seamlessly hand off a caller to a closer tower as the person travels. That ability proved very valuable in solving the 2003 murder of Carlos Martin-Gonzalez in Seminole.
Bailey, the Pinellas sheriff's detective, used the records to trace how the suspects drove from Tampa to Pinellas County. They talked on their cell phones much of the time; some calls bounced off a tower just down the street from the murder scene.
Those records eventually led to the arrest of four men in a murder-for-hire case. Some of the suspects initially tried to lie about their whereabouts the night of the murder, but realized they were cooked when confronted with the tower records.
When Bailey's partner, Detective Jim Beining, took the stand to explain the cell tower records to a jury, he saw jurors nodding their heads.
"We had charts. They were all over that," Beining said.
Two of the suspects in that case took plea deals and are serving prison time. Two others were convicted and sentenced to life in prison.
Gidari said cell phone companies want their customers to know their privacy is important to them and that it's safeguarded. But the companies also realize they must follow court orders.
"There are pressures from both sides, protecting their customers' privacy and meeting court orders and legal processes," Gidari said. "I would describe their feelings as ambivalent. They follow the law."