The search for Shannon Matthews was the biggest single investigation undertaken by West Yorkshire Police since the hunt for the Yorkshire Ripper 30 years ago.

The search for Shannon Matthews was the biggest single investigation undertaken by West Yorkshire Police since the hunt for the Yorkshire Ripper 30 years ago.

But few police inquiries countrywide can compare with the Shannon case in terms of the sheer scale of wasted resources.

More than 300 officers were diverted to the hunt for more than three weeks and the whole operation cost the force almost £3.2m.

After Shannon did not show up after a couple of nights, many senior officers were convinced they were looking for a body. But all the time they were being duped by Shannon's mother Karen Matthews.

The strategy of the investigation team was influenced by its belief - based on years of experience - that there was a very high probability Shannon had been murdered.

Detective Superintendent Andy Brennan, who led the investigation, told the trial that, in all other recorded cases, abductors who kill children have always committed the murder within three days of snatching their victim.

So when senior officers received the call to say Shannon had been found alive, they were as shocked and surprised as everyone else.