A man has been jailed for 13 years for a string of sexual offences against children over a 17-year period.
Colin Lunn, 42, from Hull, had been convicted earlier of 11 charges including four of indecent assault and two of indecency with a child.
Hull Crown Court heard Lunn had been the subject of numerous investigations by police and social services.
But police files were lost, child interviews did not take place and the investigations were repeatedly dropped.
The case only came to court after a fresh complaint was made about Lunn in 2015 and Humberside Police began a full review.
Lunn had claimed in court he was the victim of a “vendetta” and had threatened to bomb the headquarters of Humberside Social Services, despite never being charged in connection with any of the investigations against him.
The defendant, of 21st Avenue, Hull, was also convicted of one charge of attempted serious sexual assault, two offences of sexual activity with a child, engaging in sexual activity in the presence of a child, and sexual assault.
He was found not guilty of two sexual offences against a fifth child.