He told a friend he'd sleep off the alcohol in his car. His car disappeared with him. Neither has ever been found.
A Night Out in St Lucia
Sean Sargent was 24 years old, an Army officer holding the rank of Lieutenant, posted to Enoggera Army Barracks in Brisbane. He'd grown up in Mackay, Queensland, attended Pioneer State High School, and joined the Army after graduating. By all accounts from people who knew him, he was energetic, sociable, and fiercely loyal to his family — his sister later said his disappearance was completely out of character, because he called her regularly and would never have simply dropped contact.
On the evening of March 19, 1999, two days after his 24th birthday, Sean went to a house party at Orchid Street in the St Lucia suburb of Brisbane. He arrived around 7 p.m. with alcohol he'd bought at the Regatta Hotel. Later that night, at around 11 p.m., he and three friends moved on to a second party at Hawken Drive, St Lucia. He didn't stay long — there was an altercation with another man at the second party, and Sean left on his own at around 11:45 p.m.
A friend warned him not to drink and drive. Sean said he wouldn't — he told them he'd sleep it off in his car. Those were among the last known words he spoke to anyone.
A Car, and a Man, Both Gone
Sean's vehicle, a blue 1992 EB Falcon Sedan with Queensland registration 746 ENN, was never seen again after that night. Neither was Sean. Military police didn't formally report him missing until three days later, a delay that later attracted significant criticism during the coronial process.
In the weeks that followed, investigators received numerous reported sightings of Sean, including a man matching his description at Brisbane's Sportsman Hotel, and other locations around the city. None were confirmed. On April 15, 1999 — 27 days after his disappearance — someone made a failed attempt to use Sean's Defence Force Credit Union bank card. Police at the time did not request an investigation into the failed transaction from the bank, an oversight that was later raised at his inquest as one of several investigative failures in the early handling of the case.
Questions That Complicated the Investigation
The investigation into Sean's disappearance was shaped, and in the view of the inquest later complicated, by an unverified rumour about his sexuality that circulated in Army circles and was reported without any supporting evidence by the initial military investigating officer. The coronial inquest found no evidence that Sean was homosexual or living a double life, and concluded the rumour had been started by a single person without basis — but not before it had influenced the direction of early police inquiry.
Several other theories were formally considered and rejected at inquest, including the possibility he had voluntarily disappeared to join another organisation or start a new life elsewhere.
A Coroner's Finding, 18 Years Later
In September 2017, Coroner John Hutton conducted a formal inquest into Sean's disappearance. Extensive searches of the Brisbane River had been conducted in the period before the inquest, including examination of submerged vehicles — but no trace of Sean or his car was found. Hydrographic modelling of river currents was presented in evidence.
After considering all the evidence, the coroner formally found that Sean Sargent most likely died in a single-vehicle accident in the Brisbane River on 20 March 1999 — the morning after the party. His cause of death was recorded as unknown, and his body has never been recovered.
Where Things Stand
Sean Sargent's remains have never been found, and his car has never been located. His family spent eighteen years without any official determination of what happened to him. The coronial finding gave them a legal answer, if not a physical one.
If you have any information about Sean Sargent's disappearance, you're encouraged to contact the Queensland Police Service or Crime Stoppers on 1800 333 000.
Sources
Sean Sargent — Australian Missing Persons Register (Coroner's Findings)
Findings of Inquest into the Death of Sean Sargent — Queensland Courts
Missing soldier: Coroner to hand down findings — The Courier Mail