Exclusive: A child rapist will be set free from prison in South Australia next week, with a legal loophole preventing authorities from detaining him before he is sentenced for another crime.

The man, who cannot be named for legal reasons, will walk free from Mount Gambier prison on Monday, against the wishes of multiple authorities, when his five-year sentence for abusing a young girl ends.

But the following day, he’s due in a Canberra court to be sentenced for the interstate abuse of Mike Worsman, who was just 12 years old when he was violently and repeatedly raped, in the 1990s.

“The monster that offended against me, we later found out had offended against other people,” Worsman told 9News.

He and ACT prosecutors have fought for the offender to be securely extradited to the hearing for his next round of justice, but instead he’ll first be set free and trusted to make his own way across the border.

“In between where he is in jail now and likely where he’ll end up in jail again, he’s just allowed to run around in the community for 24-48 hours,” Worsman said.

ACT prosecutors have asked the territory’s chief justice to block the man’s release, but she said she had no powers to do so.

“Why are we OK with loopholes in the law that allow violent serial rapists to be free?” Worsman said.

“He could offend against other children. He’s a massive flight risk. He’s incredibly intelligent… he could disappear quite easily.”

The South Australian government has also failed to keep the man in custody. 

It says officials are working with the ACT and the Australian Federal Police to manage the man’s release.

That won’t provide any help for Worsman, whose birthday will coincide with the day of his abuser’s release.

“Someone doesn’t want to have be talking about historic rape cases but if it keeps a kid safe… that’s my community service as a parent,” he said.

Authorities theoretically have three days to stop the rapist walking free, but key sources 9News has spoken to have indicated that is unlikely to happen.

It’s hoped the offender will front up in a Canberra courthouse on Tuesday, although it’s unlikely he even has the time to get there.

A warrant will be issued for his arrest if he does not appear in court.

Support is available from the National Sexual Assault, Domestic and Family Violence Counselling Service at 1800RESPECT (1800 737 732).

Kids Helpline 1800 55 1800.