A man who used his daughters as bait to lure their schoolfriends into his house where they were drugged and indecently assaulted has been jailed for 18 years.
Martin will be a danger to children "for some time", the judge said
Former school governor Glyn Martin, 53, of Bridlington, East Yorkshire, simulated the murders of nine girls as they lay "stupefied" by sedatives.
A lawyer prosecuting Martin at Hull Crown Court said it was the worst case of systematic child abuse he had known.
Sentencing him, the judge said he would be a danger to children for some time.
Martin had earlier pleaded guilty to 57 counts of indecent assault, child abduction, indecency with a child, administering noxious substances and taking indecent photos.
Police found a hoard of 6,000 indecent photos of 2,000 other girls.
Judge Michael Mettyear said Martin was a determined and calculating paedophile.
He told him: "Those 57 offences are merely examples of your persistence, abusive conduct...
"All the evidence in the case indicates you are a determined paedophile. Your offences were carefully prepared and calculated. Your victims were young and numerous.
"You worked hard to put yourself in a position to carry out your perverted activities. You knew the risks you were running and you sought to avoid detection for your crimes. In the end it was chance that you were caught."
The court heard that Martin gave the young girls tablets, which he claimed were vitamins, shortly before they went to bed.
As they slept in a "stupefied" state he took photographs of them with placards, detailing descriptions of how he wanted to kill them, placed on their bodies.
The pictures were taken between the mid-1980s and 2003. Martin used his job as a face-painter in Bridlington to take the pictures and became a school governor in Doncaster where he took others.
He also placed adverts in newspapers appealing for young girls to befriend his two foster daughters.
The judge said there was evidence that Martin wanted to carry out further "unspeakably evil" crimes against children, including "abduction, rape, torture and murder".
The judge ordered Martin to sign the Sex Offenders' Register and banned him from working with children for life.
As the sentence was passed it was greeted with cries of "yes" from the public gallery and relatives shouted abuse at Martin as he was led away.
Det Insp Tony Burke, of Humberside Police, said afterwards: "We are very happy with the sentence. The families are also happy with the sentence and that is all that counts."
Social services officials in Doncaster, Sheffield and the East Riding have launched an independent review of Martin's activities in their areas and say they will publish their findings "in the coming weeks".