From Tom Priors book called They Trusted Men published 1996, p 40-41
The inquest accepted a similar statement from an absent youth nicknamed "Perry" said by police to be 'in smoke', on the run, to escape burglary charges. 'Perry' had been questioned on other matters some days after the murders, police said. A bloodstained knife with a long blade had been found in a scabbard in the boot of his car, when it was searched by police investigating another matter.
There were traces of A positive blood on the knife, which had been wiped in an attempt to clean it, before being replaced in the scabbard. Suzanne Armstrong's blood was A positive, but this was a blood group shared by a large proportion of the population. There was no trace of Susan Bartlett's O positive blood, also a common blood group, on the knife.
The knife was 26.67cm (10 and 1/2 inches) long and had a handle of tightly bound brown strip plastic with red strips at each end. The brand name 'Mundial' was stamped on the blade. There was a small bend at the tip of the blade which could have been caused by it hitting a solid object such as bone, police said. The knife was almost new and forensic tests showed that it had never been sharpened. There were no serrations or file marks on it whatsoever. It was in a new brown leather sheath, with yellow stitching, which could have been worn on a belt or strapped to a leg.
'Perry', who was questioned exhaustively by police, told them he found the knife near the platform of Victoria Park railway station, on the Hoddle Street side, which would be used by travellers going away from the city, between 10:20pm and 11pm on January 10. This was about 90 minutes after the murdered women were last seen alive and, if the knife was the murder weapon, police theories about the murders happening on January 11 obviously were wrong.
'Perry' had unimpeachable corroboration for the finding of the knife and an unbreakable alibi for the possible time of the murders. At the time, 'Perry' and his companions, who repeated his account of his movements, were either intent on committing, or committing, some of the burglaries with which he was later charged. He had no suspicion of the importance of the bloodstained knife, and would have been extremely unlikely to have thrown it in the boot of his car if he had, police said. He was frightened, 'shocked out of his wits' in fact, when he realised the reason for the intensity of police questioning.