The mobile telephone superflic

The Italians had called it the wolf because it was solitary and never used portable telephone. Luciano Liboni, 47 years, one taken again of justice Italian suspected of the murder of a police officer, was finally cut down in July in Rome after being recognized of visu by the police force. For only one "wolf" refusing the use of the mobile, how much suspects are confused today, fugitive decrees thanks to the portable telephone? "When a business starts, the analysis of the portable became a reflex like the investigation of vicinity", explains an officer of gendarmerie. "telephony is implied in 99 % of our investigations of stups and of steerings", a police chief of North affirms. That it is a question of determining a timetable, a route or a network of relations, the study of the fixed and mobile phone calls ­ ­ became "a quasi systematic recourse", according to a magistrate.

There was, in France, 36,7 million subscribers to mobile telephony in December 2001 and 41,6 million at the end of 2003. It is as many electronic witnesses who leave traces when the telephone is activated or in day before. When it is extinguished, a portable GSM does not emit (except if it "were bidouillé" by average techniques adapted) of signal. The signals are reflected on the 35 000 terminal-relays which net the French territory and on the million itemized bills ("facdets") which can consult the investigators on legal requisition. "an investigation of mobile telephony, it is the search for numerical stakes to advance the police investigation. To draw from wire to see what there is behind, to reconstitute a fabric of relations between telephone numbers ", analyzes Michel Riguidel, head of the data-processing department and networks at the higher national School of telecommunications (1).

Large bonnets. Lieutenant L., member of a central office of the Criminal Investigation Department, goes up international traffics between Asia and Europe. For each holder of portable implied in his investigations, it asks the "facdets" incoming calls and outgoing and the identification of the terminal-antennas by which these phone calls forwarded. "It is all the more significant to follow a suspect which usually does not reside in France. In our business, a significant guy has two, three portables on which it uses five, six chips. A large bonnet can "go up" to nine portables and fifteen chips." To change chip is not any more one argument of discretion since the operators set up, two years ago, a common data base where are recorded the Imei codes, single job numbers registered with the back of each portable. With each lighting of the telephone, this code with fifteen digits is reflected on the terminals of calls. "But this safety is not infallible, affirms a specialist. One can reprogram this number since a PC connected on the telephone."

Stars. The investigators can ask for the statements of telecommunications over variable durations, a few days or several weeks. This information is preserved during one year by the operators. Lieutenant L. is on the point of peeling a "facdet" vingt-six days, comprising 2 434 incoming calls and outgoing. "I proceed initially to a sorting of the calls by operator. When a number returns ten times in an itemized bill, I will request the identification from the operator concerned. From the terminals of calls activated, one will try to establish a geography of the business into which we inquire. When I locate a terminal GSM systematically mentioned in the incoming calls 1 hour and 9 hours of the morning, I will seek the hotels in the zone of cover of the antenna where the suspect could have spent the night." In the office of lieutenant L., a "diagram of criminal analysis" reproduces a complex succession of bonds out of stars established between various suspects starting from their telephone calls and the analysis of the address books memorized in the charts SIM which they put under seals. The OPJ uses the software of criminal analysis Anacrim and another of data banks for all "to crush".

Parades. Since the investigators exploit the data of the portable telephones, they are also confronted with the "entourloupes" imagined to mislay them. "I had to learn how to be wary of the numerical proof, affirms a police officer who worked in Corsica. It is not because you have the portable which you know who is behind the portable. A guy can "go up" to the steering by entrusting his telephone to a complicity which will start a call at the moment T of the holdup to make believe that our hooligan was telephoning of the bottom of his bed at the time of the facts." Another means "of drowning fish", the recourse to the "numbers footbridges which forward by the foreigner, explains lieutenant L. It is the principle of the prepaid telephone charts. That makes the increase of the calls very difficult ".

Hacking. The criminals also scramble the tracks by having recourse to the phreaking which is on the telephone what the hacking is with the data-processing network. It is a question in fact of being connected to the standard of a large company and of typing a numeric digital code making it possible to pass from the calls to the expenses of the company. Thus the Management of the monitoring of territory (DST) was charged to inquire into pirate calls since the standard of a bank of the Valley-of-Marne bound for Morocco and Spain in the days preceding the attacks by March 11, 2004 to Madrid. Lastly, Michel Riguidel affirms that it is also necessary to be wary of the portables whose invoices do not mention any call: "an always extinct portable, it is quite as suspect. That wants to say that one does not want to point out oneself."

(1) Author of Safety at the numerical era, Hermès-Lavoisier editions.