It was the last High Court retrail that was easily the most expensive at $2,338,809, with lawyer fees costing $1,404,503 and disbursements the rest.
Disbursements for which legal aid can be provided for include research, investigators, DNA and blood testing, forensic expenses, court filing fees, witnesses, accommodation and reasonable living costs for legal representation, some general office expenses, agents' fees, and specialist reports.
Legal Aid Services director Michele McCreadie said the service did not have information about who received fees for the original trial and appeal.
For the trial and associated Court of Appeal, Privy Council and Supreme Court proceedings, the legal aid was paid to the lead provider Michael Reed, QC, who was responsible for the payment of lawyers in David Bain's defence team and other costs.
Colin Withnall, QC, was part of Mr Bain's defence team for seven years following the first failed appeal.
He said legal aid was there to provide legal representation to those who could otherwise not afford it.
"When all this started David Bain was a student... people simply can't afford the amount of money that it costs to do this."
"People have a right to proper legal representation, and if they don't have the funds to pay for that themselves than the state should pay to ensure that justice is not only done but seen to be done."
While paid legal aid for two hearings before the Court of Appeal, Mr Withnall, along with long-time Bain supporter Joe Karam, worked many unpaid hours.
"For all the years that Joe and I worked to investigate it, there was no state funding. Joe paid a lot himself in the early days but ran out of money, and after that we did it pro bono publico - for the good of the public."
University of Otago law professor Kevin Dawkins said even taking in to account legal representation, experts, preparation time it "does seem a lot of money".
"I gave a lecture towards the end of 2009 and the figures at that stage was just over $1.4 million... and I thought that was looking like a closing final figure."
The Legal Services Act 2011 introduced a requirement to invoice for legal-aid services within a specific time frame, which was currently three months.
The information from Legal Aid Services noted that David Bain is not receiving legal aid to assist with his application for compensation. This is being considered at present by a retired Canadian Supreme Court judge.
