Marina Tsiamis was a 21-year-old clerical worker in a government office building in Canberra's south in 1981 when she was befriended by two elevator technicians.

She said the trio were riding on top of a lift at Woden's Scarborough House on December 16, 1981 when one of the men with her, Ian MacKenzie, was crushed to death.

The Sydney woman said her various mental illnesses, including post-traumatic stress disorder, bipolar disorder and paranoid schizophrenia, had sprung from her witnessing the tragic death of the 26-year-old technician.

But Ms Tsiamis failed to convince the Administrative Appeals Tribunal (AAT) that she was on top of the lift when Mr MacKenzie met his death or that her experience in 1981 was the cause of her mental problems.

Instead the tribunal heard evidence from three psychiatrists that it was more likely that her drug abuse during the 1990s was the cause of her psychiatric problems, and rejected her bid for workers' compensation.

Ms Tsiamis claim for post-traumatic stress disorder, first lodged with Federal workplace insurer Comcare in November 2011, was refused by the insurer which said there was no connection between her illness and her public service employment which ended in 1982.

Her appeal against the decision was held in March in Sydney where the Tribunal heard evidence from the surviving technician, named simply as "Mr O".

Mr O refused to give evidence about the day of Mr Mackenzie's death for fear he would incriminate himself, but did say that Ms Tsiamis had ridden on top of the lift four or five times before the tragedy on December 16.

According to the Tribunal's findings, the skylarking was something "hard to imagine happening in a government workplace today."

"By today's standards, riding on top of a lift in the workplace would almost certainly be regarded as serious and wilful misconduct," wrote Senior Tribunal Member Jill Toohey and her colleague Dr Sah Hooi Toh.

"It may well have been regarded in the same way 30 years ago."

The tribunal heard that Ms Tsiamis had led a colourful life since 1981 including a stint in the all-female Sydney show band The Debutantes in the 1980s.

By the late 1990s though, the former public servant had taken to drugs, attempted to overdose on heroin and pills in 1999 and and was first admitted to psychiatric hospital in 2002.

But she failed to convince Senior Member Toohey and her colleague that she was even on top of the lift when Mr MacKenzie died, after the transcript of the coronial inquiry into the incident was examined.

Even if Ms Tsiamis was on the lift, the tribunal found, her experience could not be found to be a cause of her undoubted mental health issues.

"We cannot be satisfied, on the evidence before us, that Ms Tsiamis was present on top of the lift at the time of the accident," the tribunal members wrote in their judgement.

"Even if we were satisfied that she was, we are not satisfied that there was a causal connection between her employment and the serious illness that she developed many years later."

CORRECTION: An earlier version of this story reported that Marina Tsiamis had told the Administrative Appeals Tribunal that she was "thrill-seeking" when she rode on top of a lift at Woden's Scarborough House on December 14, 1981, and witnessed a fatal accident. Ms Tsiamis did not use that term. Tribunal records confirm Ms Tsiamis said in evidence that she rode on top of the lift because lift mechanics had offered her a ride to a lower floor.