The mystery man killed by a train in Pakenham nine years ago. Credit:Victoria Police On a Thursday night more than nine years ago, one of these unknown people was killed on railway tracks near Pakenham station. Moments before his death, he paced around an empty train carriage. Occasionally, he placed his face in his hands, as if in anguish. Then he got off and walkd in front of a city-bound train. The first driver to hit him didn't realise. The one that followed, about 10 minutes later, did notice and called the authorities. The dead man wasn't carrying any papers. He had no tattoos or other identifying marks.

The jacket the Pakenham man was wearing, with a logo that reads “Valley Statesman Rugby League”. Credit:Victoria Police For the next couple of years, police tried to establish his identity. His appearance indicated that he was of South Asian background. That no one reported him missing points to a recent emigre. Publicity yielded tips in Canada, Nepal and India, however DNA tests on family members ruled those out. One lead was found to be alive. An inquest did not shed any new light. A locker at the state mortuary containing an unidentified body. Credit:Eddie Jim This week police made a fresh call for help from the public.

"It's a needle in the haystack kind of file, but it's something that's got to be done," says Detective Senior Constable Mick Van Der Heyden, the latest investigator tasked with finding out the man's identity. There are dozens of these John and Jane Does on the missing persons DNA database at the Victorian Institute of Forensic Medicine, where unexpected or suspicious deaths are examined for the Coroner. Most of the bodies brought into the mortuary are identified within 24 hours. It's rare for them to stay in the fridge much longer than that, especially when they're intact. Often, the unidentified dead will come in fragments, where skeletal remains have washed up on a beach or been found in bushland. If a person isn't identified quickly, they will undergo a series of procedures, including CT scans, fingerprinting and DNA tests to try and find a match. Dental records can be the quickest way to unpick the lock.

If none of that is successful, police will try a public appeal and hope someone comes forward. Bodies are usually kept for up to six months or a year before they are buried in an unmarked grave. "We have so many cases that come here on a daily basis, every single one has a sad story behind them," says Dr Jodie Leditschke, manager of the team of scientists and doctors at the Victorian Institute of Forensic Medicine. "But they all have to be identified, they all have to be handled in a respectful manner. We still have to follow a process, for us it's important to follow that process." One of the biggest challenges in identifying a body is when the person has come from overseas. Checking international databases can take a lot of time. But sometimes the smallest identifying feature can lead to those cases being solved.

A pair of jeans helped identify Swedish man Olof Dennis Grinsvall, 22, months after he was hit and killed by a train at East Camberwell railway station. Investigators were facing an uphill battle when no one came forward to report that the young man had gone missing after his death in September 2012. His body might have remained unidentified if police didn't catch a lucky break, thanks to his brand of pants. Multiple appeals for information by frustrated police revealed that Mr Grinsvall was wearing Crocker jeans, a Swedish brand, when he died. That fact prompted a Swedish newspaper to report on the case, which Mr Grinsvall's family happened to read about in Lulea, a coastal city in northern Sweden. At the time they were unaware he was in Australia. He had only been here for three days.

After the family contacted authorities, Mr Grinsvall's body was able to be identified through dental records and DNA technology. His remains were subsequently repatriated to Sweden. Efforts to track down the unidentified Pakenham man include checking immigration records from the time he may have arrived in the country and looking for anyone who has overstayed their visa. An Interpol "black notice", which is shared with 190 countries, is also being compiled. One of the key features police want the public to think about is what the man was wearing at the time of his death, a blue and red jacket with a "Valley Statesman Rugby League" logo.

The jacket had been discarded by its owner a few months earlier. Someone who worked with him might remember him wearing it. "There's no doubt the family are out there and they're wondering what's happened to him," says Detective Senior Constable Van Der Heyden. "We're just waiting on that one phone call." If this story has raised concerns for you, the following services can assist: Lifeline: 13 11 14lifeline.org.au

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