Karate champ jailed: 37,000 indecent images of children found on one computer

Stephens, 50, had set up nine hard drives and several computer screens to hoard thousands of images satisfying his sickening secret fantasies.

The karate star even kept a diary of his life and encounters with his victims behind lock and key in a first-floor room of his Parkstone home.

For 20 years, Stephens’ nasty ways of getting his kicks remained a secret, until he showed a naked photo of a child to someone last spring, and they raised the alarm.

Sergeant Andy Bell, who headed up the inquiry, says officers found Stephens in his hideout.

Sgt Bell said: “Effectively his front room was just a den of photos, videos and DVDs.”

The hi-tech crime unit took over the investigation.

At its height, 13 officers were going all around the country interviewing victims dating back to the 1990s.

One computer had 37,000 level one indecent images, and the team had to wade through between 500,000 to one million files in total.

Sgt Bell added: “The sheer amount of storage meant this was the biggest job Dorset Police and high tech crime unit has ever had to deal with.”

Footage showed Stephens setting up a covert camera in his bathroom to record his victims – once making eight secret movies over a fortnight.

They helped police search for the tiny camera, but it was never found, even when the high tech squad swept the property with radars.

Sgt Bell said: “He is a worrying character and has got some pretty dark fantasies.”

This double life is in stark contrast with Stephens’ public image as a worldwide ambassador for karate.

Sgt Bell said: “I think people are shocked about what has come out.

“His den was always behind a locked door so if you went round there, you’d think everything was absolutely normal.

“When we went round he was on his computer as we walked up the stairs.

“If that door had been locked, we would have kicked it down, but a neighbour would never have known what he was doing.”