A sick pervert who abused his own step grandson is facing years behind bars after he was caught on camera when he video-called an online sex worker.

Accused Werner B. was taking part in a live, two-way sex show when the hostess reportedly noticed a child in the background, a court in Germany heard.

The 37-year-old woman is quoted in local media as telling judges at the Regional Court of Aachen, in North-Rhine Westphalia: “I saw a young boy’s face slightly blurred in the background.”

She added: “Having a child present in the room during my performance didn’t feel right to me.

“So I just asked him who the boy was and what he was doing.

“He changed the position of his webcam so I could have a look myself. I was totally shocked.”

Sickenly, the adult worker revealed, the lad was acting out sex acts he had learned from somewhere.

The witness told judges: “That was when I told myself, ‘I’ll have that guy pay for that!’

“So I continued doing my show as if nothing had happened, but secretly filmed his webcam window with my mobile.”

The woman informed police immediately after signing out of the show in February.

Police tracked down and seized 57-year-old trucker Werner B. at his home in Merzenich within hours, the court heard.

Hiding his face behind a beige folder, Werner B. has pleaded guilty in court, according to local media.

Investigators reportedly discovered paedophile content on his computer and mobile.

His wife reportedly claimed she had been totally unaware of his perversion.

The couple have a handicapped son and had custody of their two step-grandchildren.

The behaviour of the victim had worried the child’s teachers who had reportedly suggested therapy sessions.

Werner B. said in court: “They kept calling us up. I became quite exasperated.”

The trial is ongoing.