Sex offender Robert Hind was jailed indefinitely because of the danger he posed to the public.
But the pervert had his sentence reduced to three years – because of a legal anomaly.
Hind, 47, had been jailed twice previously for indecently assaulting boys before his last court appearance in 2011.
He then pleaded guilty to being involved in sexual activity with another teenage boy.
He was sentenced to indefinite imprisonment for public protection at Bradford Crown Court in September, 2011.
But the sentencing judge, Judge Jonathan Rose later admitted that in passing the sentence he had taken account of Hind’s previous convictions for indecent assault.
The judge said he had overlooked an amendment to the Sexual Offences Act which “for reasons best known to the lawmakers of this land” meant he could not take account of Hind’s previous convictions.
Having considered his original view of the appropriate determinate sentence Judge Rose concluded that Hind should instead serve a jail term of three years for the latest offences.
The court at Bradford in 2011 heard Hind was only charged after another abuser, who was locked up for his part in the boy’s ordeal, made a statement to the police.
Barrister Stephen Wood submitted that Hind, who has a low IQ, had committed the offences under the “malign influence’’ of the other man. But, Judge Rose said the defendant had been unable to resist offending against the boy.
Judge Rose said he had come to the view that Hind posed a significant risk of committing further sexual offences, particularly against young boys, and that such offences would cause serious psychological harm.
Police released CCTV images of the last confirmed sighting of Robert Edward Hind last Friday, after he was reported missing on the evening of December 11.
Footage retrieved by detectives captured him with another man at Huddersfield bus station at 9.20am on Wednesday, December 11.
He had gone missing from an address in Dewsbury.
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