One of the state's most notorious criminals has walked free from prison and immediately been given a taste of what life on the outside might be like.

Key points: Michael Guider walked from Long Bay Jail shortly after 3.00pm carrying two garbage bags

Michael Guider walked from Long Bay Jail shortly after 3.00pm carrying two garbage bags He was jailed for the manslaughter of Samantha Knight and abusing more than a dozen children

He was jailed for the manslaughter of Samantha Knight and abusing more than a dozen children He will live in a halfway house attached to the jail under a strict five-year supervision order

Michael Guider served 17 years in jail after pleading guilty to the manslaughter of Sydney schoolgirl Samantha Knight.

He walked from Sydney's Long Bay Jail around 3.00pm carrying a garbage bag in both hands, a large tumour visible on his leg.

As he slipped into a silver car which was to drive him to a halfway house, members of the public shouted, "Dog!".

A short way into the drive, the 68-year-old was targeted for several minutes by a man wearing a high-vis jacket and riding a motorcycle.

At one point the rider took out his mobile phone and appeared to snap a photograph of Guider in the back seat.

Michael Guider walks free from Long Bay Jail. ( ABC News )

At another set of traffic lights, the motorcyclist seemed to be speaking to a pedestrian as he repeatedly pointed at the car.

Moments later, the rider sped off, leaving Guider's car to carry on to its destination.

Strict conditions on release

Guider was sentenced in 2002 for killing nine-year-old Knight and was already serving time for abusing more than a dozen other children.

His sentence expired in June and his release came after a Supreme Court judge this week rejected the Government's application to keep him in prison for at least another year.

Samantha Knight disappeared near her Bondi home in 1986. ( AAP )

Guider will be placed under a five-year supervision order with 56 strict conditions, including living at a halfway house attached to Long Bay Jail.

Attorney-General Mark Speakman conceded the 58-year-old was at high risk of reoffending if left unsupervised and so authorities would be watching him closely.

During the Government's application to keep Guider in jail, the court was told he was willing to take anti-libidinal medication.

Guider's lawyer, Matthew Johnston SC, said he had engaged in rehabilitation and already had limited exposure to the community, including wearing an ankle bracelet.