The Crown’s star witness, who was given an indemnity against prosecution in return for giving evidence against his former boss, ex-NSW minister Tony Kelly, has told a District Court jury that due to health issues, “I can’t remember anything about anything”.

Arriving in a wheelchair and wearing a short sleeved-shirt, a knitted sleeveless vest, grey gloves and a panama hat, Gilbert “Laurie” Brown, Kelly’s former chief of staff, said he couldn’t remember giving evidence at the ICAC, being criminally charged himself or that he’d been given an indemnity against prosecution in return for giving evidence against three former Labor ministers: Kelly, Joe Tripodi and Eddie Obeid, who have been charged with misconduct in public office.

On Tuesday afternoon, the jury of five men and four women retired to consider their verdict in the trial of Anthony Bernard Kelly, 77, the former Labor leader in the upper house.

The jury heard allegations that in May 2010, as infrastructure minister, Kelly authorised and signed a reworked cabinet minute which, if accepted by the government, could have delivered billions of dollars to a privately owned water infrastructure company, Australian Water Holdings (AWH), which the jury heard had links to the family of former Labor kingpin Obeid.

Brian McGlynn, an expert retained by the Department of Premier and Cabinet at the time, told the jury that he and a panel of experts had compiled a draft cabinet minute in April 2010 recommending against the government entering into a private-public partnership with AWH.

The jury heard that claims by the prosecution that McGlynn’s draft cabinet minute should have killed off AWH’s ambitions, but the following month, Kelly submitted a substantially revised minute to the Budget Committee of Cabinet. Crown prosecutor Brett Hatfield, SC, said the changes to McGlynn’s minute were not just cosmetic or stylistic but “reversed the main recommendation”.

Hatfield told the court that the Kelly cabinet minute “included a number of false and misleading facts” as well as “significant omissions and, in some cases, direct lies”.

One of the lies was that the Kelly minute now suggested that AWH’s proposal had been solicited by the government, which, according to the prosecutor, was not true, the court heard.

“I have never seen anything like it,” said senior public servant Dianne Leeson when asked about the changes to the minute. In her evidence, then-CEO of Sydney Water, Dr Kerry Schott, said she was “absolutely shocked” when the Kelly minute was shown to her.

The prosecutor told the jury that Kelly knew the amendments to McGlynn’s original minute were false and aimed to benefit AWH.

Kelly was asked to withdraw the minute, which could have cost the taxpayer billions of dollars. AWH stood to receive between $25 million to $35 million per year for 35 years.

The jury heard allegations that the metadata of the email had been deliberately scrubbed so that the identity of the authors of the reworked minute could not be ascertained.

The prosecutor submitted that Kelly did not do the redrafting himself, or that he personally stood to gain, but that the minute was changed at his instigation, he signed it and submitted it to the Budget Committee, which, while not the full cabinet, had the effect of binding the government.

He did this to benefit AWH, Hatfield submitted.

The star witness, Brown, 69, told the jury he couldn’t remember anything about AWH. He also claimed to have a foggy memory about AWH’s chief executive, Nick Di Girolamo, whom the jury heard was lobbying widely on AWH’s behalf and may have been involved in providing the background information for Kelly’s reworked cabinet minute.

Phone records were shown to the jury which indicated there were 13 calls between Brown and Obeid between March and July 2010.

However, Brown’s evidence was that he only ever spoke to Obeid a couple of times a year, during which they would swap recipes.

Former premier Kristina Keneally gave evidence that in mid-2010, she was lobbied about AWH by then-Labor backbencher Obeid. She raised with him that his family had a connection with AWH, which he did not deny, she told the jury.

A week after her call with Obeid, she said that Kelly complained to her that public servants were frustrating his office’s dealings with AWH. Keneally told the jury that Kelly was well aware that Obeid had an interest in the outcome as she raised with Kelly her “additional concern about the connection of the Obeid family”.

In his summing up, Judge John Pickering said it was up to the jury of seven women and five men to determine whether Brown’s lack of memory “is genuine, real, fake” or due to medical conditions. He also warned the jury not to speculate about any consequences for Brown whether he did or did not comply with his indemnity agreement, or what Tripodi or Obeid may or may not have done.

Earlier, the Crown prosecutor told the court that Brown was a “very unimpressive witness” who did have some health issues, “but you might have thought he was not really trying to remember things”.

Defence barrister Patrick Griffin, SC, submitted that Brown had faced a series of health challenges, including meningitis, a heart attack and kidney failure. Griffin also suggested that any alterations to the cabinet minute were solely at the hand of Laurie Brown.

Griffin called two former Labor ministers, Terry Sheahan and Richard Amery, and read a statement from the late former attorney-general Michael Egan. Their evidence was that busy ministers had to rely on the honesty and integrity of their chief of staff.

However, the prosecutor told the jury that Kelly had first submitted – then withdrawn – his cabinet minute in May. In August 2010, a month after Brown lost his job in Kelly’s office, the minister resubmitted the cabinet minute. Again, it was withdrawn.

Kelly’s barrister put to the jury that submitting a cabinet minute “for debate and consideration falls significantly short of being misconduct that is serious and meriting criminal punishment”.

Start the day with a summary of the day’s most important and interesting stories, analysis and insights. Sign up for our Morning Edition newsletter.