A Queensland court has ordered Matthew James Cox to stand trial over allegations that he murdered his wife, Tayla Black, and their 11-week-old daughter, Murphy Margaret, in Rockhampton in August 2023.

The decision follows a multi-day committal hearing in the Rockhampton Magistrates Court, where prosecutors and defence lawyers examined witness testimony and evidence before determining whether there was sufficient material for the case to proceed to the Supreme Court.

Cox, now 34, faces two counts of murder. Prosecutors allege that on 8 August 2023, he fatally attacked his wife and infant daughter at the family's home in Park Avenue, Rockhampton. Police allege he later travelled to Brisbane and presented himself at the Fortitude Valley Police Station, leading officers to conduct a welfare check that resulted in the discovery of the two bodies.

During the committal hearing, the defence focused heavily on Cox's mental health history. Lawyers questioned more than a dozen witnesses, including family members, former colleagues, bartenders and people who had known Cox before the alleged killings. The defence argued that this evidence was relevant to understanding his psychological condition at the time of the alleged offences.

Among the evidence presented, Cox's father told the court that a psychiatrist had raised concerns in 2022 after Cox reportedly disclosed thoughts about harming family members during a hospital admission. According to the father's testimony, Cox later described those statements as a "cry for help" and said he would never act on them.

The hearing also examined Cox's behaviour in the months leading up to the alleged killings. Witnesses gave differing accounts of his mental state, with some describing noticeable personality changes following treatment for mental health issues, while others recalled him appearing positive and engaged with family life. Bartenders who served him on the day of the alleged offences told the court they did not believe he appeared intoxicated.

After considering the evidence, the magistrate ruled that the prosecution had presented sufficient material for the case to proceed to trial. The matter will now move to the Queensland Supreme Court, where a jury will ultimately determine whether the prosecution can prove the charges beyond reasonable doubt.

Cox remains in custody pending future court proceedings. He has not been convicted of the offences, and the allegations against him have not been proven in court. Under Australian law, every accused person is presumed innocent unless and until found guilty following a fair trial.

The case has attracted significant attention across Queensland because of its tragic circumstances and the issues surrounding mental health evidence that are expected to feature during the upcoming Supreme Court trial.