Ron Lane, the nephew of victim Barry Lane, said the images of Vlassakis walking through the pre-release centre's car park, accompanied by another man, were a shock and triggered flashbacks.
"Seeing the photo for the very first time of him now is a shock to the system and gives flashbacks on why he was in [prison]," Mr Lane said.
"It's just a memory of everything that has happened. You just wish that you could turn back the clock and this sort of thing was just a bad, horrible dream."
Vlassakis, the youngest of the perpetrators in what became known as the "bodies in the barrels" murders, was jailed for life in 2001 with a 26-year non-parole period backdated to his 1999 arrest. He pleaded guilty to the murders of Fred Brooks, Gary O'Dwyer, David Johnson and his half-brother Troy Youde.
His testimony helped convict John Bunting and Robert Wagner, who were jailed for 11 and 10 murders respectively, and accomplice Mark Ray Haydon, who was released in 2024 after serving a 25-year sentence.
The Parole Board granted Vlassakis parole last year. The state government attempted to block the decision, but it was upheld by the Parole Administrative Review Commissioner last month.
Vlassakis will now spend up to 12 months at the pre-release centre while the Parole Board monitors his progress and decides on conditions for his eventual release into the community. Parole Board chair Frances Nelson KC has previously said Vlassakis would be subject to standard conditions.