Earlier this month,Federal Court Justice Anthony Besankoruled in a defamation case won byThe Age,The Sydney Morning Herald andThe Canberra Timesthat Roberts-Smith was involved in the killings.

Besanko found that the disgraced war hero kicked Ali Jan off a cliff while he was handcuffed and was implicated in his unlawful execution,as well as those of the two Easter Sunday prisoners.

Besanko largely based his findings on the evidence of Australian special forces soldiers who witnessed the incidents and testified against Roberts-Smith. The standard of proof required for a civil court judge to make a finding is lower than that for a criminal court.

The decision of the CDPP not to criminally prosecute Roberts-Smith raises major questions about why it took Commonwealth prosecutors almost three years to answer an obvious,albeit complex and novel,legal question concerning the use by police of information uncovered by the Brereton inquiry.

The AFP provided the CDPP a brief of evidence involving the Ali Jan cliff incident in about May 2020,at which time Commonwealth prosecutors began to seek internal and external legal advice about the potential problem of evidence tainting,said a source with knowledge of the process who was not permitted to speak publicly.

The laws under which the inspector general operates prohibit the use of certain information derived directly or indirectly from suspects who attended coercive hearings undertaken by Justice Brereton.

“The office of the CDPP has spent way too long making a decision,delaying the ability for the OSI-AFP teams to restart the impacted probes,” said one official source,who was not authorised to comment publicly.

The CDPP declined to comment.

In June last year,this masthead asked Attorney-General Mark Dreyfus if he had sought advice about delays in the Roberts-Smith investigations,potential problems around the handling of Brereton inquiry information and why the existing federal police probes had not been handed to the OSI.

Dreyfus declined to answer the questions last June and when asked on Tuesday said they were a matter for the CDPP.

The OSI’s existing investigations into Roberts-Smith are not affected by the same problems facing the AFP inquiries because the OSI,which is headed by former judge and top prosecutor Mark Weinberg,adopted a different approach to handling Brereton inquiry information.

The OSI is a special agency that works in partnership with the AFP and was created in 2021 to investigate alleged war crimes.

The OSI has urgently taken over handling of key federal police witnesses linked to the cliff death and Easter Sunday killings,including Special Air Service Regiment (SAS) soldiers who had agreed to testify against Roberts-Smith.

On Tuesday,the AFP said it had sought and abided by internal and external legal advice after it received the information from the Brereton inquiry in 2018 that led to its Roberts-Smith probes.

“The AFP relied on this advice to manage the legal risks known at the time,including how to use the information referred from the[Brereton] inquiry for a criminal investigation,noting some of the information was obtained through the use of powers which compel individuals to attend hearings (coercive powers),” it said.

The AFP’s position was supported by some lawyers from the office of the Australian Government Solicitor,sources with knowledge of the process said.

However,after receiving differing legal advice from external barristers,the CDPP believed there was a risk of a High Court challenge by Roberts-Smith and the prudent approach was to start over.

Legal experts and official sources said the decision to restart the probe with new investigation teams underscored the catastrophic decision by Roberts-Smith to launch defamation action.

The case forced him and his special forces co-accused and witnesses to swear under oath and into the public domain,where their testimony can be accessed by the OSI and AFP without fear of evidence tainting.

Leading criminal law barrister Robert Richter,KC,said:“The calamitous decision[by Roberts-Smith] to launch and run the defamation trial means that significant re-examination by the OSI of the evidence which would or can be used in any criminal trial processes becomes essential.”

Richter said the CDPP’s decision not to prosecute was most likely reached after arduous deliberation and that he had utmost faith in Special Investigator Weinberg to avoid any legal minefields in connection to the relaunched probes.

“What we do know,or can assume,is that whether Ben Roberts-Smith or anyone else is to face grave criminal charges,there will be bitterly contested legal debates about admissibility of some of the evidence,” Richter said.

SAS sources,not authorised to speak publicly,have told this masthead that the delay to an already traumatic investigation process that has taken five years would deeply frustrate witnesses. On Tuesday,one AFP witness told this masthead he had been contacted by federal agents and assured that new OSI-AFP teams would take over his role in the new inquiries.

“It is a massive blow for all the SAS witnesses who have stood up and agreed to co-operate with the federal police five years ago,” said the witness,who cannot be identified because of a non-disclosure order issued in the defamation case.

“The massive delays all seem incompetent to me. It doesn’t sit right,” the witness,an Afghanistan veteran of the SAS,said.

Earlier this month,Justice Besanko ruled Roberts-Smith had intimidated witnesses,a possible breach of the criminal law. Last week,this masthead revealed the AFP sent a witness intimidation brief last November to the CDPP in the hope of charging the ex-soldier. That brief of evidence is unaffected by the CDPP’s decision that the AFP’s handling of Brereton inquiry material may have exposed a future war crimes prosecution to legal appeal.

• Crossing the Line by Nick McKenzie will be published in July,to pre-order clickhere.