WHILE their 14-week-old baby died Dixielee Link and Vaughan Murray smoked drugs, watched a movie and played video games.
The baby, also named Vaughan, was found in the bedroom of their Bundamba house by Murray on September 23, 2009.
A coronial inquest found while baby Vaughan's death was suspicious, no cause of death could be determined.
The inquest heard Link and Murray had "inconsistent" versions of the day's events, however, both denied any involvement in their child's death.
The inquest heard the baby was put to bed after a day out.
Murray said he placed a bottle in Vaughan's mouth then left the room to play videos games, while Link was watching a DVD.
Both were smoking cannabis, and Murray said they had used heroin during the day. However, Link, who had been on the methadone program while carrying Link, denied this.
Murray told the court he "forgot about" Vaughan until the movie finished and then went to check on him. He said he found the baby not breathing and screamed out.
An ambulance was called and Vaughan was taken to Ipswich Hospital. He couldn't be resuscitated and was declared dead at 9.07pm.
Link and Murray were briefly interviewed by police at the hospital. Link took part in another recorded interview; however, Murray declined any further participation in the investigation.
The inquest heard from three medical experts who all said while smothering couldn't be ruled out the cause of death couldn't be established.
Baby Vaughan was found to have bruising to his face, and five broken ribs. Forensic pathologist Dr Nathan Milne found the ribs had been broken between three to six weeks before and had started to heal.
Murray and Link denied any actions that would have broken the ribs, such as squeezing. Link said Murray would throw the baby into the air and catch him; however, he denied doing this and all three medical experts said this would not have caused the broken bones without further heavy squeezing.
While the cause of death couldn't be found, Sudden Infant Death Syndrome was ruled out by Dr Milne as no evidence of it could be found by Royal Children's Hospital consultant paediatric specialist Dr Catherine Skellern.
Coroner John Hutton found no cause of death could be determined.