They should have known it was too good to be true – this is the moment two cocky sat-nav thieves were nabbed after trying to break into a van, only to find a policeman and his dog lying in wait.

The stunned thieves tried to flee, but German Shepherd Krueger proved that four legs are better than two and mauled one of the crooks, who cried out in pain and later needed stitches.

The unmarked white Transit had been parked near shops with a sat-nav system still stuck to the window.

Within 30 seconds of the driver leaving the vehicle, three youths – including one on a bike – had pulled up.

Officers hiding in another unmarked vehicle gave a running commentary of suspects’ movements nearby. As one thief smashed the window, the dog handler and Krueger burst out and gave chase.

One of the teenagers made a half-hearted attempt to take shelter behind a nearby wheelie bin.

He quickly gave up when he was attacked by Krueger. A second tracksuit-clad thief was arrested, face down, on a patch of grass near the busy road. A third got away amid chaotic scenes.

Yesterday’s sting was one of a number in Knowsley, Merseyside, as part of a blitz on crooks in the area. Six people have been arrested in four such operations. Det Chief Insp Martin Andrew, of Merseyside Police, said the thief would not have been mauled by the dog had he obeyed orders to stop.

Mr Andrew said the operation could not be classed as entrapment, because the vehicle was typical of many that would be parked in the area every day.

He credited the operation with a 70 per cent reduction in theft from vehicles, adding: “We will continue to use every trick in the book to catch as many criminals as possible.

“We have had success in reducing crime figures in Knowsley, and that will only further our determination. We will be using these decoy vehicles on a regular basis, and the criminals don’t know which ones are decoys because we are swapping them around so much and using some of the 10,000 vehicles seized last year as well as newer cars.

“Knowsley, for criminals, is not a place to frequent.”

Last year, the Express & Star published dramatic pictures of sat-nav thief Carl Bennett breaking his way into a vehicle, thinking that the driver had left his hi-tech navigator on display.

A hidden camera in the car captured a close-up of his face, and the 30-year-old, from Bridge Street, Bilston, was later jailed for 17 weeks.

Figures released at the time showed an average of 331 of the gadgets are stolen each month in the West Midlands, but August saw a sharp rise with 503 thefts.

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