A Canberra woman who accused her former partner of rape nearly five years ago has admitted she made up the claim, which saw him spend months behind bars.

As a five-day hearing into the matter began in the ACT Magistrates Court, Sarah-Jane Parkinson, 28, unexpectedly pleaded guilty to making the false claim in March 2014 and even staging a crime scene.

Parkinson, a former police worker, also pleaded guilty to possessing a prohibited weapon after she was found with capsicum spray.

Her identity had previously been suppressed by laws aimed at protecting the identities of sexual assault victims.

The original allegations were made against Parkinson's former partner while he was a prison officer at Canberra's jail.

He was remanded in custody and spent nearly four months in Goulburn jail, before the charges were dropped.

The couple first met in 2011, became engaged, and even bought a house together.

By 2013, the romance had soured, the pair split, and Parkinson formed a new relationship soon afterwards.

Court documents show that on the day of the false claims, she sent her new partner a blank text message, which was their code for a call for help.

Police arrived at the house to find Parkinson on the kitchen floor with apparent injuries and her jeans undone. She was groaning and complaining of a pain in the stomach.

The agreed statement of facts shows she told police she couldn't remember much, but in later interviews she claimed to recall more and more, telling police her former partner had not only raped her but made her kneel on the ground outside and hit her head on a retaining wall.

She also told the Federal Court that after she was raped by her former partner, he had hosed her off in the garden.

Prosecutor Trent Hickey told the court there was no sign Parkinson had been hosed, or that a hose had been run at the property, arguing the false claim had been planned.

"The Crown's submission is that she planned to come to this story from the get go," he said.

Parkinson later admitted she staged the scene to make it more convincing, upturning a peg basket, planting a condom wrapper at the side of the house, inflicting injuries on herself and pretending to have lost her memory.

It was also revealed investigators found the accused man had been at his parents' house with others around the time of the alleged incident.

She will be sentenced in January.