An Australian man living in India has been set free on the same day he was convicted of sexually abusing disadvantaged boys and young men.

Paul Henry Dean, 75, has been repeatedly accused of abusing dozens of children over almost four decades spent living among poor communities in India under false identities.

In a court case that lasted 17 years, Dean was convicted on charges of "unnatural sex" with 12 boys and young men.

The charges were laid in 2001.

Dean was sentenced to three years in jail and fined the equivalent of $235, but released on bail the same day, pending an appeal.

Local police said he will live and work in the town where he offended — Vishakhapatnam, on India's south-eastern coast.

A local police inspector, who spoke to ABC News on condition of anonymity, said there was no risk to the local community.

"No, the matter was in court, he was already convicted," he said.

"If a new complaint is registered, then he will be arrested".

Dean posed as priest, doctor to access disadvantaged kids

Dean fled Australia on a fake passport in 1976, escaping a warrant for his arrest on fraud charges in Western Australia.

He was the subject of a Four Corners report in 2009, which exposed the horrific details of his abuse and the way in which Indian authorities turned a blind eye to his offending.

Dean masqueraded as a priest, and then a doctor, to gain access to the most disadvantaged children.

He worked among lepers and the poor, switching between several different aliases.

Some of the charities he worked alongside raised money from Australian donors.

Indian police said Dean roamed India for decades without a valid passport or visa.

After he was charged in 2001, the case was shuttled between different courts for 17 years, and he was released on bail and moved towns.

Ravi Varma, the investigating police officer in the original matter, told ABC News there are many reasons why the court case took so long.

"There were legal obstacles because he is Australian," Mr Varma said.

"Sometimes he was not available to court, sometimes he absconded."

Victim statements given to police investigating the 2001 case were obtained by Four Corners.

"[Dean] made me watch pornographic videos, then have sex with him like it was done on the videos. At first I refused but he said I'd lose my job, so I gave in," one read.

'No doubt there is corruption'

Bharti Patel, from UK-based child protection organisation ECPAT, said cases like Dean's are not unusual in countries where the justice system is beset by delays.

"In some of the countries where the most vulnerable children live, there are huge, complex systems in place and no doubt there is corruption," Ms Patel said.

"This is the kind of situation and environment that is often exploited by abusers like Paul Dean, who get away with it.

"They know that they will either never be caught, or if they are caught, they will get out of it by paying some of the law enforcement officers or relying on the fact that their case will never go to court".

Ms Patel said local agencies do not do enough to protect the victims.

"Children are often off the radar," she said.

"Often no effort is made to reach out, to identify and safeguard the children that people like Paul Dean have exploited".