Philip Ruddock says he would have raised concerns about the death penalty had he known the Australian federal police planned to share intelligence on the Bali Nine with Indonesia in 2005, when he was attorney general.

But Ruddock says no one in the Howard government had power to give “any direction politically” to the AFP on its fateful decision, which has faced renewed criticism in light of the imminent executions of Andrew Chan and Myuran Sukumaran.

Barrister Bob Myers, who tipped the AFP off about another Bali Nine member, Scott Rush, said the police had “not a legal but a moral obligation” to ensure a waiver of the death penalty as a condition for sharing intelligence.

Myers said the AFP would have known executions were likely when their agent wrote to Indonesian police the day after Myers’s tip-off to request surveillance and suggest they “take what action they deem appropriate” if they suspected the group had heroin when leaving Indonesia.

Myers, who contacted the AFP on behalf of Rush’s family on the eve of the group’s journey to Bali, said he and his police contact were “used” by the AFP, which already had passport details for all except Sukumaran.

Myers said the AFP always knew there was a risk that people might die as a result of their actions. “They had no right or authority to do it,” he said.

Ruddock told Guardian Australia that he had “no clear recollection” of his meeting with Myers.

“I certainly at no stage was informed of this matter [by the AFP] and if I had been, I think it is fair to say given my position on the death penalty, I would have been very conscious of it and said [that] others should be,” Ruddock said.

According to AFP guidelines in 2004, the attorney general had decided that police would adopt a future policy where a lack of guarantees of no death penalty could be grounds for refusing requests from overseas police.

The guideline was adopted in 2009. It followed a federal court judge ruling in 2006 that while the Bali Nine were the “authors of their own harm”, the case showed a need for the minister and the AFP chief to address the death penalty issue when the AFP itself was making requests overseas.

Ruddock said in 2004 he could only apply the policy when ruling on extraditions, and the justice minister, Chris Ellison, who had oversight of the AFP, was not “in a position to give [the AFP] any direction politically”.

Asked if he imagined AFP officials regretted the outcome, Ruddock said: “I can’t speak for the Australian federal police but I can’t imagine that people wouldn’t be looking back over what has happened and tried to ask themselves, could we have dealt with it differently?

“I can’t imagine that they wouldn’t.”

As Canberra continued to press its 11th-hour case with Jakarta to grant clemency, Ruddock said he “would like to think there’s still hope but I can’t speak with certainty”.

“My focus is on seeking to have the penalties waived and I do that having been a member of Amnesty for 40 years and now being the co-chair of the parliamentary group that is seeking to have the death penalty removed universally,” Ruddock said.

Myers said revelations that the suspected mastermind of the Bali Nine syndicate was living freely in luxury in Sydney after winning the lottery hammered home how the worst punishment was borne by low-level players.

He said a royal commission should be held to examine the AFP’s conduct of the case “because it’s almost as if police didn’t want to find any more other than petty criminals like 19-year-old Scotty Rush”.

Chan and Sukumaran had their transfer to Nusa Kambangan, the island of their planned execution, postponed this week.

Peter Russo and Stephen Keim – former lawyers for Pakistani doctor Muhamed Haneef, who was wrongly accused by the AFP of terrorism offences in 2007 – were speakers at a mercy vigils for Chan and Sukumaran in Brisbane on Wednesday.

Russo, a solicitor and now Queensland Labor MP, told Guardian Australia that only the AFP could disprove his belief that “there was no reason they couldn’t have stopped them from leaving Australia”.

“What always worried me about the AFP was [that] they always left me with the feeling [of], let’s get a conviction at any cost,” he said.

“I think the AFP definitely need to give a more forthcoming explanation and they have to accept some culpability for what occurred.

“They’ll never do this but they need to come out and say we made a mistake, we made an error of judgment, we wouldn’t do that again.

“I think that would be cold comfort to the families but it would be good for their process to acknowledge they got it terribly wrong.”

Keim, a barrister, told Guardian Australia the actions of the AFP regarding the Bali Nine were “wrong on all levels”.

He said the police had violated national policy by “causing nine Australians to be placed in danger of being subject to capital punishment”, 14 years after Australia had signed up to the second optional protocol to the International Covenant on Civil and Political Rights.

“And the action was both vindictive and deliberately bloody-minded since any anti-drug importation objectives could have been achieved by allowing the individuals to land in Australia and arresting them at that time,” Keim said.

“The failure to make a full explanation as to how these events occurred and who were responsible for them adds to the concern about the actions which were taken.”

The AFP have declined to go into details of the Bali Nine operation but defended their actions in a statement to Fairfax radio this month, saying they had not been “in a position to prevent these people from travelling to Indonesia”.

“The AFP had no evidence or lawful reason to detain, much less arrest or charge, any member of the Bali Nine before their departure from Australia,” they said.