Quanne, 12, was plucked off a Granville street on July 27, 1998, just minutes after she left home to catch the train to Strathfield Girls High School.

After almost two decades, Vinzent Tarantino, 49, attended Surry Hills police station to be interviewed by detectives on Sunday.

Mr Tarantino, who has been a suspect for 18 years, was subsequently charged with enticing Quanne off Factory Street in Granville, when he was 31 and living around the corner in his family home on Second Street.

He detained her with the intention of holding her for ransom but then murdered her by causing "substantial injury," police allege.

Police have returned to Mr Tarantino's childhood home in Second Street, Granville, for a second day on Tuesday to search for Quanne's remains.

It is just 700 metres from the Diec home, where Quanne's parents Ann and Sam have remained since 1998 in case their daughter walked back into the lives.

"If Quanne did return and we're not here, then she won't know where we have gone," Mr Diec said in 2003.

It's unknown what prompted Mr Tarantino to suddenly speak to police after 18 years. However he had allegedly been walking around Surry Hills with a 35-centimetre kitchen knife on Sunday in an episode that has mimicked other apparent breakdowns he has had in the past.

​Until Sunday, Mr Tarantino appeared to live a normal life with his de facto partner, CBD clothing store manager Michelle, in her apartment in Sydney's inner west.

Yet, Fairfax Media can reveal that he allegedly went to great lengths to hide a chequered past.

He changed his name from Victor David Gerada to a mash-up of Pulp Fiction's creator, Quentin Tarantino, and the film's violent protagonist, Vincent Vega.

In 2006, he had a violent altercation with his then-partner when she found out that he had not disclosed the truth about his earlier life, according to official documents from the time.

His "earlier life" included a shocking incident in 1997, the year before he allegedly killed Quanne, in which he witnessed the aftermath of a triple bikie murder.

He was working as security guard at the Blackmarket Cafe nightclub in Chippendale when three Bandidos bikies were killed in a bloody shoot-out in the basement.

He was one of the first to see the three bodies and described to authorities the "appalling scene" that confronted him.

After giving evidence against the bikie gang, he tried to commit suicide and left the family home to go into a witness protection program, court documents show.

He moved around Sydney constantly to avoid people knowing who he was and spiralled into mental illness that became psychotic at times.

He had violent confrontations with police on several occasions, including throwing a Molotov cocktail at officers and spraying another with petrol, when they tried to prevent him from self harm.

However, Mr Tarantino's upbringing as a child in Granville had been relatively normal.

He was a sports-mad teenager in a family of three children and did well at school. He gave up a carpenter's apprenticeship to work as a Kings Cross security guard.

A neighbour in Second Street, Peter Youssef, told AAP on Monday that the Gerada family had lived in the Granville home since the 1960s and Vincent would sometimes come back to visit his father, Godwin.

In bizarre comments made to a magistrate in Central Local Court on Monday, he said his brother and partner had been murdered in retaliation "for what I have done".

His brother, Allan, and partner, Michelle, are both alive and well.