And in the weeks, months and years after, throughout her trial for Azaria's murder, her wrongful conviction, three years in prison, the subsequent Royal Commission and several coronial inquests, the letters kept on coming, filling up boxes and chests and filing cabinets in the family home.

In them, the public sympathised, sent threats, told her of their own lost children and family dramas, and kept her up-to-date on life on the outside.

It was after her release from prison that Chamberlain-Creighton took up the National Library of Australia's offer to hold the letters for her, but not after she had gone through and meticulously catalogued and filed them in colour-coded folders.

Chamberlain-Creighton herself is still intrigued by the letters and by her own presence in the lives of so many people she is never likely to meet.

"It fascinated me that all the men in one family would write, and in another one it was all the ladies that were writers. It seemed like it ran in families," she said.

Thanks to these letters, according to the library, the 1980s is the most documented period in Australia's history, and when playwright Alana Valentine heard about them, her interest was piqued.

She gained special permission to go through the files, and said it was a unique glimpse into the minds of ordinary Australians.

"What I really wanted to see was what people do reach for in those moments of confusion and helplessness," she said.

"How do they put, in words to a stranger, what it is that they want to say? And I certainly found that in abundance."

The resulting play, Letters to Lindy, opens at the Canberra Theatre on Tuesday, and is a fascinating snapshot of 1980s Australia.

Speaking at the National Library on Sunday, Chamberlain-Creighton spoke of how overwhelmed she had been by the steady stream of letters she received while in prison, and said she had to enlist the help of other inmates when sorting through them.

And more than 30 years later, she is still receiving emails about her case.

"We get a minimum of 1000 a year," she said.

Valentine said going through the files at the library had been a researcher's dream, especially as Chamberlain-Creighton had written a precis for many letters, and often annotated them in the margins.

She had even devised a star system as a way of categorising their contents, with seven stars reserved for those that were the "most extreme" of their kind.

"It was like having Lindy sitting on your shoulder," she told the audience yesterday.

Letters to Lindy is playing at the Canberra Theatre from August 9-13.