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EDITIONS
 Friday, 20 December, 2002, 13:28 GMT
Handsets provide police with clues
Mobile keypad, BBC
Mobiles are helping the police with many inquiries
When the police want to know about you, your habits and lifestyle, they do not need to ask friends and relatives.

Instead they can find out an enormous amount just by looking at what you do with your mobile phone.

Who you call, the text messages you send and receive, where your bills are sent to and the services you have signed up for are proving valuable to police investigations.

Phones are even being made to reveal messages and information that their owners may have thought were long deleted.

Use and abuse

Most recently information gained about a mobile was used to convict Stuart Campbell, the man found guilty of murdering teenager Danielle Jones.

Although precise figures are not available, the police are believed to be making hundreds of thousands of requests every year for information about mobile owners.

Stuart Campbell
Campbell: handset helped to convict him
The majority of these requests are for basic information such as the name and address associated with a particular phone number.

Mobile phone numbers are allocated in blocks of at least a million, making it relatively easy for police forces to work out which network a particular number is from.

This can help track people down if bills are sent to an address different to the one held in police records.

Details of a bank account or credit card used to pay a bill can also open up new lines of enquiry, as can the types of services that a particular customer has signed up for.

Contact list

Police forces must get the permission of the Home Secretary to listen in to your phone conversations and see the words you send in text messages.

But they have much freer access to data about who you call or send messages to.

This can help police reveal patterns of behaviour and sometimes help them break into rings or gangs of criminals.

Receiving a text message, BBC
Phones hold a lot of data about their owners
Jack Wraith, spokesman for the Mobile Industry Crime Action Forum (Micaf), said this information could help cast doubt on false alibis.

He said even though the location finding ability of most UK phones was poor, it could still help police narrow down where someone was.

He said the ability to work out where a phone was being used depended on whether it was being used in a built-up area and how many base stations were close by.

There is no technology on-board a mobile phone that will reveal its exact location. In rural areas a single base station serves customers in a radius tens of kilometres across.

Finding phones

In built-up areas base stations serve smaller areas, but often it is only possible to locate a phone's use down to an area a few hundred meters across.

The different base stations that a phone talks to as its owner travels can also reveal the route someone took.

But Mr Wraith said this crude location finding proved crucial in convicting Stuart Campbell who used Danielle Jones' phone to send text messages and make it look like she was still alive.

"It's not an exact science but it is based on probabilities of evidence," he said.

Future phone technologies will make it much easier to locate phones and many operators are working on services that prompt users with alerts when they get close to cash machines, restaurants or petrol stations.

Phones recovered from criminals can also help the police.

When you erase something on a hard drive on a PC, your computer does not scrub the data out. Instead it just gives the block a label saying that it can be overwritten.

Similarly on the Sim cards inside mobile phones, when you delete text messages and lists of calls, the information could remain on the card and not be overwritten for a long time.

Forensic data firms can readily recover this information.

There are isolated reports of some criminals attempting to eat the Sim card from their mobile phone for fear that it will provide evidence that could convict them.


Key stories

Investigation

The trial
See also:

19 Dec 02 | England
03 May 02 | Science/Nature
19 Dec 02 | Technology
14 Aug 00 | Science/Nature
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