A Sydney man who brazenly sexually assaulted five young girls after dragging them off the street has been jailed for more than seven years.

Richard Crowe, 45, was arrested at his home in August last year, nearly 25 years after the crimes were committed.

The Sydney District Court was told Crowe had told his young victims “scream and I will kill you”, before he sexually assaulted them between 1989 and 1991.

Crowe also forced his victims, aged between nine and 17 at the time of the offences, into derelict buildings or stormwater drains at knifepoint during the attacks.

"If you don't shut up I have a knife and I will kill you," he told the 17-year-old victim he attacked as she was walking to a north Sydney train station.

Another victim was grabbed as she was walking alone to Sunday school.

Crowe was arrested in August 2014, nearly 25 years after the crimes were committed. (NSW Police)

In sentencing Crowe to a maximum of 12 years’ jail, Acting Judge Anthony Garling said Crowe’s crimes had deprived his victims of the childhood they deserved.

“It was predatory behaviour,” Acting Judge Garling said.

“He set out to physically attack – with one exception – young girls.

“Children going about their daily life, no doubt feeling safe and enjoying their youth as all children are entitled to.”

Crowe was finally arrested after the Cold Case Justice Project was able to link him to the crimes using DNA evidence.

Crowe, who was aged between 19 and 21 when he abused the girls, suffers from a range of mental health issues.

The court was told he had been diagnosed as a pedophile.

With his sentence discounted 25 percent for entering early guilty pleas, Crowe will spend a maximum of 12 years behind bars.