Damien Karnstein, 55, changed his name to a 1970s horror movie vampire before mimicking the torture rituals on his victim.

Yesterday he was caged for seven years when he was snared more than three decades after carrying out his brutal crimes.

And the Mail can reveal Karnstein had worked as a volunteer tour guide at Hartlepool's Maritime Experience – with his bosses and visitors unaware they had a child rapist in their midst.

>> Child rapist led double life

But Karnstein was asked to leave the site after Hartlepool Borough Council staff spotted him behaving inappropriately in May 2008, before the matter was reported to police.

Karnstein's attacks, dating back to the 1970s, went undetected until he appeared in court late last year on child porn charges.

Police had uncovered a series of sickening child porn images on computer discs in a raid after being alerted by workmen doing repairs on his Hartlepool home.

Further searches revealed a stash of children's toys and dolls and a blow-up male doll dressed up as a schoolboy on a bunk bed.

After reading press reports about the charges, his victim walked into a police station and finally divulged the horrors he had been subjected to years earlier.

When confronted by detectives, Karnstein confessed all and yesterday he admitted a string of child sex crimes at Teesside Crown Court.

The court heard how he regularly abused the youngster and raped him twice.

At around the same time he changed his name by deed poll from Stephen Ogden to Damien Karnstein after the Hammer House of Horror character Count Karnstein.

The Dracula-like figure, played by actor Damien Thomas, appeared in a trilogy of Hammer films. Shaun Dodds, prosecuting, said: "The character is involved in torture and sacrifice.

"In his video interview the complainant mentioned the defendant would sometimes tie him up on a bed for pretend rituals involving fake blood and daggers."

Mr Dodds said the abuse against the boy escalated from sexual touching to two instances of rape.

The rapist would also ply his victim with alcoholic cocktails he had learned to make working in a hotel.

During the horrors, Karnstein would tie up his victim and subject him to mock sacrifices using ritual daggers and fake blood.

But Karnstein remained at large until police raided his house in December 2008 and found 24 indecent images of children he had printed off or were saved on floppy discs.

Some of the pictures featured children as young as 12 and included four at level four, the second highest category of explicitness.

Karnstein pleaded guilty to two counts of indecent assault and two charges of rape.

He had earlier admitted 16 counts of making indecent images of children and one of possession of indecent images.

Christine Egerton, mitigating, described Karnstein as a loner who changed his name after being bullied.

She said: "He was a horror movie fan at the time and so changed his name to a name that he liked.

"But there was nothing sinister about it."

Ms Egerton said he was a collector and the toys and dolls were not intended to entice children.

She added: "Mr Karnstein accepts that he must have known what he was doing was wrong."

Karnstein, of Benmore Road, Hartlepool, was ordered to sign the Sex Offenders' Register for life and was also made the subject of an indefinite Sexual Offences Prevention Order preventing him from unsupervised contact with anyone under 18 after he is released.

Judge David Bryant said: "It is clear that this boy was abused by you seriously and for a substantial period."