The Chatham triple murderers might never have
been convicted if not for a controversial spy camera
network.

Danai Muhammadi was flagged as a suspect after his Renault
Megane was clocked driving to Chatham Hill by automatic numberplate
recognition cameras (ANPR).

Police have used them to snap all drivers on main roads
- guilty or not - since 2006. Kent Police has led the way
in much of the technology.

But ANPR has come under fire from home secretary Theresa May,
who in 2010 said it must be better regulated.

Muhammadi, 24, was yesterday found guilty of of three counts of murder and two

of attempted murder. His friend, Maidstone nightclub bouncer Farhad

Mahmud, 35, was found guilty of the same charges.

Det Ch Insp David Chewter believes ANPR it is a vital tool.
He led the murder investigation - codenamed Operation Raft
- by the Kent and Essex Serious Crime Directorate.

He said: “Within a few short hours I was told the car had come
into Kent.

“I was able to focus the whole investigation around that
information and that directly led me to other suspects.”

It was a young detective, DC Daniel Mead, who performed the type
of check which is now routine.

He told the trial: “I submitted Mr Muhammadi’s address in
Chatham into a search on the police national computer.

“The search showed his vehicle had entered Kent the previous
evening through the Dartford crossing. It was almost
instant.”

Danai Muhammadi's Renault Megane
on camera in Chatham

His bosses radioed to the officers, who were driving to
Coventry to inform Muhammadi as next of kin. He became a
suspect.

The mammoth database is divisive because it stores every
movement of every vehicle.

Police refuse to reveal each camera's location, though the main
ones in this case were on the A229 and Dartford Crossing.

Nick Pickles, director of privacy campaign Big Brother Watch,
said: “Clearly what happened in this case was horrific, but you
can’t base an entire country’s policy on one case. ANPR remains a
serious privacy issue that needs addressing urgently.

“Few people probably even realised their journeys were being
tracked in this way, with the data held forever. The system isn’t
used to track criminals and suspects, it’s indiscriminately
tracking every one of us.”

Mr Chewter said: “For a law-abiding citizen like myself, I’m
just driving down the road and I’m doing it for a lawful
purpose.

“We only go and look for vehicles used in criminality or when
we’re protecting vulnerable people.”

Police also
tracked Mahmud’s phone through his phone company’s general packet
radio service data (GPRS).

The GPRS logs clocked when his phone received data from its
nearest transmitter - which plotted him travelling into
Chatham.

Mr Chewter said: “It gave us a story which we could go through
the interviewing process with, and of course then they’ve got to
answer questions around it. ‘Well how come your phone is in Chatham
directly after the fire?’”