BALI - An Australian beauty student caught at an Indonesian airport with 4kg of marijuana in her boogie-board bag is relying on the testimony of an alleged rapist today to save her from a firing squad.

The case of accused drug smuggler Schapelle Corby has captivated Australia since she was arrested in October at Denpasar airport.

Now, an Australian prison inmate who has been called her best chance of escaping the death penalty, has been flown into Bali to give evidence on her behalf.

Victorian remand inmate John Patrick Ford will testify that Corby was an unwitting courier used by a ring of Australian drug traffickers - a move that puts his own life at risk.

In an 11th-hour move, Ford arrived in Bali in handcuffs and under tight security and will be held at Denpasar police headquarters until he takes the stand today.

In order to avoid a gangland hit on their star witness, Corby's lawyers said they would seek a court order for Ford's evidence to be heard in secret.

In what could potentially be a lifeline for Corby, Ford signed a statement for her lawyers and told police he overheard a conversation among other prisoners that Corby was the victim of a domestic drug smuggling operation gone wrong.

Ford told Corby's lawyers he could not live with himself if he failed to testify in the case.

Corby has maintained her innocence, saying the pillow case-sized stash must have been planted there during the domestic transit leg of her trip, between Brisbane and Sydney.

Granting an adjournment last week to give Corby's legal team more time, judges at the Denpasar District Court warned that Ford's evidence could backfire on Corby.

However, her main financial backer, Gold Coast businessman Ron Bakir, said Ford could be Corby's last chance to beat a possible firing squad.

"We've got to take every opportunity and use it and explore every possible door and he's a key witness right now and you know he could be the possible lifeline of Schapelle Corby," he said.

The trial comes ahead of a visit to Australia tomorrow by Indonesia's new President Susilo Bambang Yudhoyono and amid the heavy press coverage in Australia that may cloud a trip billed as a fence-building exercise.

Australian Federal Police chief Mick Keelty has described Ford's evidence as hearsay on hearsay and said the Indonesian judicial process should be left to run its own course.

Ford is on remand on charges of rape, aggravated burglary, threatening to kill, unlawful imprisonment and assault.

His lawyer Paul Vale said Ford was pleading not guilty and would contest all the charges in his May trial.