A 23-year-old man has been charged with manslaughter following the death of his five-week-old baby son in Kiara, a suburb in Perth's north-east. Western Australian Police confirmed the charges on Friday, 6 November 2026.

According to police, the investigation began after the infant suffered serious injuries at a residence in Kiara on 10 August 2026.

The baby was taken to a nearby medical centre for urgent medical attention before being transferred by ambulance to Perth Children's Hospital, where he received further treatment.

Despite medical efforts, the infant died on 15 August 2026 as a result of his injuries.

Detectives from the Western Australia Police Force subsequently launched an investigation to establish the circumstances surrounding the baby's death.

Following several months of inquiries, investigators identified a 23-year-old man, Matthew Wayne Winmar, as the person allegedly responsible for the offences.

Police arrested the man at a residence in Katanning, in Western Australia's Great Southern region, on Thursday, 5 November 2026.

Following his arrest, detectives charged him with manslaughter in connection with the death of his infant son.

The investigation also uncovered allegations involving a woman in her twenties who was known to the accused. Police charged the man with two counts of common assault in circumstances of aggravation or racial aggravation.

Authorities confirmed that both matters are being treated as family violence-related incidents.

After the charges were laid, the accused appeared before Perth Magistrates Court. He made no application for bail during the court appearance.

He is scheduled to appear before Stirling Gardens Magistrates Court later in November 2026 as the legal proceedings continue.

The case has attracted attention because of the age of the infant and the seriousness of the allegations. Investigations involving the death of a young child require detailed examination of medical evidence, witness accounts and the circumstances surrounding the injuries.

Western Australian authorities have not released further details about the specific circumstances of the alleged assaults or the full evidence collected during the investigation.

The charges represent a significant development following the baby's death in August. Police have confirmed that the investigation has progressed to the court stage, where the allegations will be examined through the legal process.

The accused remains entitled to the presumption of innocence, and the manslaughter and assault allegations have not been proven in court.