"It's the community's eyes and ears we're looking for," said Detective Senior Sergeant Ed Kinbacher, who is leading the investigation. "It's somewhat unexplained as to what happened between those relatively short distances."
Quayle was unconscious when he was found by the passer-by, who tried to revive him, but he was pronounced dead by paramedics shortly afterwards.
Kinbacher said police were keen to speak to witnesses, and hoped members of the public might be able to "fill in the blanks ... because quite simply we do run out of CCTV footage - it gets much scarcer once you turn on to Spence Street and head south along that section of roadway".
Senior Constable Russell Parker said Quayle's death was being treated as suspicious. "We are calling for anybody with information," he said. "We do know that this man was located deceased in that area at 3.30am, we don't know at this stage what his movements were prior to that."
Kinbacher said there were "some injuries which may cause some concern, whether a third party was potentially involved which caused those injuries ... What the circumstances are which may have caused those injuries, we do not know". He added, however, that "other alternatives" to murder were not out of the question.
Police established a crime scene along a block of Spence Street yesterday, diverting traffic. Quayle and his brother lived around the corner, on Lumley Street.