The 17-year-old was hit by a car and killed early on March 1, 1987, while walking home from a party along Kent Street, Deakin.

The driver fled, and has never been brought to justice.

But new information on the case was provided to Fairfax Media by a friend of Troy, Mark Plows, who says he confronted a key suspect in the case, after hearing him badmouthing his friend. He says the suspect, who has not been named for legal reasons, told him that Troy deserved to die, and was a "piece of shit".

The suspect drove a similar colour, make and model panel van as the one police believe struck Troy. He was at the same party and near the scene on the night, and there were inconsistencies in his statements to investigators.

Traffic Operations Detective Sergeant Jason Kennedy, in charge of the cold case investigation until this year, has since interviewed Mr Plows and taken a formal statement.

Detective Sergeant Kennedy also re-interviewed the owner of the van, and two friends who were with him on the night of the death.

But the veteran officer warned that the new information had not been enough to move the case forward.

Police hold faith in the original inspection of the suspect's car, performed in the hours after Troy's death, which found the damage to its front end was inconsistent with the evidence found at the scene.

"The difficulty that you've got is, [the suspect's] vehicle was examined on the night and was found not to be consistent with the evidence from the scene," Detective Sergeant Kennedy said.

"In some sense, I don't know where you could go with that; police have provided evidence in the inquest to say that basically he was ruled out because the damage wasn't consistent," he said.

Mr Plows' claims that the suspect was badmouthing Troy could not be corroborated by police and his allegation that an officer had phoned him to bully him into staying quiet was described as "highly unusual".

"We've got to deal with evidence, we've got to deal with facts, we've got to be able to corroborate stuff … it makes it difficult," Detective Sergeant Kennedy said.

"Yes, we'll investigate it to the nth degree, but at the same time, there's numerous inquiries that we're undertaking.

''I guess at the end of the day, 'yeah, he had a panel van which was similar, which was in the area at the time, and was stopped on the night by police at a roadblock on Kent Street.

''[But] those investigators deemed the damage inconsistent."

Detective Sergeant Kennedy said the case was ''not a done deal''.

"It's a difficult one because, is it a tragic accident or was there some malice to it?"