BY NAOMI HARRIS
In the darkness, an unmarked police car moves slowly along a normal city street. The officer in the back concentrates on a hand-held screen as he angles a camera carefully out of the window.
He is looking for subtle, tell-tale signs that could suggest an apparently innocuous-looking house is being used to grow cannabis on an industrial scale.The thermal imaging camera, or infrared snoop, can detect cannabis factories with pin-point accuracy by picking up variations in heat through most building materials.
As cannabis plants require high temperatures and light levels to germinate and eventually flower, rooms which appear to emit more heat than normal are honed in on by specially trained officers for closer inspection.
The infrared snoop was used by Devon and Cornwall Constabulary for the first time in the run-up to National Drugs Week.
Det Con James Gledhill, drugs liaison officer at Heavitree Road police station, said he and his team used a camera on loan from a manufacturer to gather intelligence, but they were hoping to purchase their own soon.
He said the camera was used to seek out premises and support existing intelligence work.
"By using this device we can be far more selective and precise in when we choose to execute a search warrant," said Det Con Gledhill.
"We can go to a magistrate, show them the footage and act quickly without the grower suspecting a thing."
Cannabis growers are notorious for hacking into the mains electricity supply to siphon off power for high-energy lamps.
The cost to the electricity supplier can run into thousands.
"A well-organized factory can make up to £600,000 a year," said Det Con Gledhill. "It's often seen by organised crime networks as a quick, easy and less risky way to make money. This is then fed into other criminal activities, such as people trafficking."
The cameras cost around £7,000 each, but Det Con Gledhill said this would be quickly recouped in the disruption of drug dealers.
The device can also be used by officers to locate missing persons or search buildings.
"We would like one of these units in Exeter for immediate access to officers in the community," added Det Con Gledhill. "It is a versatile bit of kit that brings real results."
Tomorrow: A former addict from Exeter talks about why he is trying to put the misery of drugs behind him.