A former prison guard accused of murdering three friends on an outback motorcycle adventure 40 years ago has made a second bid for bail.
Bruce John Preston was charged in April with the 1978 murders of Karen Edwards, 23, Timothy Thomson, 31, and Gordon Twaddle, 21, near Mount Isa.
Preston was "doing it tough in custody" where he had to be kept in isolation because he is a retired senior prison officer, his barrister Russell Pearce told a Brisbane court on Friday.
The court heard that a police report from 1980 had emerged since Preston first applied for bail in June.
Mr Pearce said the Crown's case was "very weak" and contained a lot of "conjecture and innuendo".
Preston had been a person of interest after having been found in possession of a distinctive BMW 750 motorcycle belonging to Mr Thomson weeks after the murders.
The three friends were last seen at a caravan park on the morning of October 5 following their arrival in Mount Isa as part of a motorcycle journey from Alice Springs to Melbourne.
Their bodies were found 19 days later in bushland, 12km north of Mount Isa. All three died from gunshot wounds.
Brisbane Supreme Court Justice Peter Davis reserved his decision on the bail application.
Australian Associated Press