Glory Kwangtreng was jailed for a total of 14 years at the Old Bailey for raping a 22-year-old French student as she visited Karl Marx's grave in Highgate, north London, and assaulting another woman four months later.
It is understood that Judge Michael Coombe has ordered his criticisms to be passed to Sir Peter Imbert, the Metropolitan Police Commissioner.
Kwangtreng, 32, described by the judge as 'very dangerous as far as women are concerned', was arrested five days after the rape in May last year, when the girl was working as an au pair.
But he was released after initial police inquiries appeared to confirm his alibi that he was working that day.
Judge Coombe described this as 'an unfortunate error of judgement', and it is understood he ordered his criticism of the alibi check to be passed to Sir Peter.
The following September, Kwangtreng struck again. A 24-year-old designer woke to find him at the foot of her bed in the early hours. He indecently assaulted her.
The court heard that Kwangtreng had only been released in March last year from a jail term for indecently assaulting a 10-year-old girl.
Kwangtreng, of Kentish Town, north London, denied both the rape and the indecent assault in two separate trials.