"We met many times with the judges," he said. "It was more than 1 billion rupiah [about $133,000 at the time] to get a verdict lower than 20 years –15 or 16 or 17 years like that. So then we had a deal on that." A young girl is guided to place a candle as part of an Amnesty international vigil. Credit:Getty Images said the risk was now too big for them and that the [1 billion rupiah] was not enough." At this point, Mr Rifan​ says he made a fatal miscalculation. He believed the judges were bluffing. "I thought they were only joking. I thought they would return back to the 20 years if I didn't come up with more money."

But, on February 14, 2006, Chan and Sukumaran​ were sentenced to death. The sensational claims by Mr Rifan​ that the initial trial of the pair was deeply corrupted were revealed following a joint investigation by Fairfax Media and the former host of SBS' Dateline program Mark Davis. It comes on the eve of the execution of the two Australians, who have been told they will die at midnight on Tuesday, or soon after. Australia's Minister for Foreign Affairs Julie Bishop said Mr Rifan's​ allegations were "very serious". "They call into question the integrity of the sentencing process," she said. "[It] underlines why we continue to request Indonesia to allow the judicial commission to finalise its review ... An execution is an irrevocable step and I believe that these hearings and these appeal processes should be concluded before any decision is taken."

However, she admitted that there was no sign that Indonesia would heed widespread calls, reinforced by UN secretary Ban Ki-moon on Monday, that they back away from the killings. Indonesia's foreign ministry queried why the allegations had been made so close to the execution of Chan and Sukumaran​, and asked where the proof was. However, Mr Rifan​ says he has gone public with details of the alleged corruption because he has been waiting for the judicial commission, the Indonesian body that safeguards the probity of judges, to investigate the alleged requests for bribes. Mr Rifan​, Chan and Sukumaran​ have all given affidavits to the commission but none had been interviewed, even though the investigation formally started almost two months ago. Meanwhile, it emerged that Indonesia's Attorney-General and chief advocate for executing drug felons, H.M. Prasetyo​, was a senior figure in the office of the Attorney-General in 2006 when it allegedly intervened to insist the Bali nine duo get the death penalty.

Mr Prasetyo was deputy attorney-general at the time, a senior bureaucratic position. He left later that year to embark on a political career, Ever since his appointment as attorney general, Mr Prasetyo​ has led the push for the executions of Chan and Sukumaran​ and other drug convicts, repeatedly saying their various legal appeals will fail. Mr Prasetyo​ has also said that the executions should take place before Indonesia's judicial commission – which examines claims of judicial wrongdoing – completes its investigation into the claims. He says the investigation is irrelevant. Mr Prasetyo​ could not be reached for comment on Monday. Fairfax Media is not suggesting he knew about the alleged negotiations for money nor was involved in the alleged intervention from Jakarta.

But as the most senior deputy attorney-general at the time, in charge of general crimes and the examination of legal actions, there is a clear potential for a conflict of interest. Mr Rifan​ has vowed to provide further details of the alleged corruption to the judicial commission, if they ever get around to contacting him despite starting their probe almost two months ago. Meanwhile, lawyers for Chan and Sukumaran​ echoed Ms Bishop's concerns about the "disturbing" allegations. "This is unfair," Indonesian human rights lawyer Todung​ Mulya Lubis told reporters. "People should not be executed if the judgment came from a defective process. "We appeal to the Attorney-General. We appeal to the President. In the name of due process of law, fairness and justice, do not do the executions."