Sir Keir Starmer may be called as a witness at inquiry into the wrongful conviction of Andrew Malkinson, with a decision on a probe now expected in the coming days.
Mr Malkinson spent 17 years in prison for a crime he did not commit after his wrongful conviction for rape.
Ministers are considering whether to launch a public inquiry into the miscarriage of justice after the Criminal Cases Review Commission (CCRC) confirmed last week it will look into its handling of the case.
A review already has support from Conservative backbenchers including Sir Robert Buckland, a former justice secretary, and David Morris, who served as the self-employment tsar under David Cameron.
Files obtained last week by Mr Malkinson, 57, show that the Crown Prosecution Service (CPS) knew that forensic testing in 2007 had identified a male DNA profile on the victim’s vest top that did not match his own.
Mr Malkinson was prosecuted before Sir Keir ran the CPS as Director of Public Prosecutions (DPP), and the case never crossed the Labour leader’s desk. When fresh evidence came to light, the CPS immediately discharged its duty and passed the new evidence to the defence.
Lord Ken Macdonald, Sir Keir’s predecessor as DPP between 2003 and 2008, has already backed a public inquiry, leading to calls from Tory MPs for the Labour leader to give his own opinions about the case at any future public inquiry.
A source close to Alex Chalk, the Justice Secretary, said the details of what an investigation may look like continue to remain “in the balance”.
“We’re looking at options as to the best way to do it and the most efficient way of doing it to get the result that the public expect,” the source said, adding that ministers are hoping to reach a conclusion “in the coming days”.
‘Need to get the facts’
Angela Rayner, Labour’s deputy leader, has described the treatment of Mr Malkinson as “absolutely appalling”, adding: “We need to get to the facts of what’s happened.”
Mr Malkinson was formally declared innocent by the Court of Appeal on July 26 after DNA linking another man to the crime was produced.
His appeals had twice been rejected by the CCRC, to which he made his first application in 2009, leading to calls for Helen Pitcher, its current chairman, to answer for the commission in public after weeks of refusing to do so.
In a statement given outside court last month, Emily Bolton, Mr Malkinson’s solicitor, urged MPs to reform legal institutions to make them “transparent and accountable”.
“Force them to apologise and learn the lessons from Andy’s case – otherwise we will see more wrongful convictions, more trauma, more justice denied,” she said.
The Labour Party declined to comment.