Growing Presence in the Courtroom: Cellphone Data as Witness
By ANNE BARNARD The New York Times July 6, 2009
Mikhail Mallayev, who was convicted in March of murdering an orthodontist whose wife wanted him killed during a bitter custody battle, stayed off his cellphone the morning of the shooting in Queens. But afterward, he chatted away, unaware that his phone was acting like a tracking device and would disprove his alibi - that he was not in New York the day of the killing.
Darryl Littlejohn, a nightclub bouncer, made call after call on his cellphone as he drove from his home in Queens to a desolate Brooklyn street to dump the body of Imette St. Guillen, the graduate student he was convicted this month of murdering.
The pivotal role that cellphone records played in these two prominent New York murder trials this year highlights the surge in law enforcement's use of increasingly sophisticated cellular tracking techniques to keep tabs on suspects before they are arrested and build criminal cases against them by mapping their past movements.
But cellphone tracking is raising concerns about civil liberties in a debate that pits public safety against privacy rights. Existing laws do not provide clear or uniform guidelines: Federal wiretap laws, outpaced by technological advances, do not explicitly cover the use of cellphone data to pinpoint a person's location, and local court rulings vary widely across the country.
In one case that unsettled cellphone companies, a sheriff in Alabama told a carrier he needed to track a cellphone in an emergency involving a child - she turned out to be his teenage daughter, who was late returning from a date.
For more than a decade, investigators have been able to match an antenna tower with a cellphone signal to track a phone's location to within a radius of about 200 yards in urban areas and up to 20 miles in rural areas. Now many more cellphones are equipped with global-positioning technology that makes it possible to pinpoint a user's position with much greater precision, down to a few dozen yards.
To determine where a suspect's phone was in the past - as in the Mallayev and Littlejohn cases - investigators use company records that show a phone's approximate location at the beginning and end of a call.
To track suspects in real time, law enforcement officials must ask a phone company to "ping," or send a signal to, a phone; for the effort to succeed, the phone must be turned on, though it does not have to be in use. The police can then use a vehicle with signal-tracking equipment to narrow down the location.