Police have been castigated for their “absolutely unacceptable” approach at an inquiry into gay hate crimes, amid renewed criticism of poor record-keeping.

Two former unsolved homicide squad detectives were due to face the NSW inquiry on Monday, but proceedings were temporarily adjourned after counsel assisting Peter Gray said he had received documents from police just 10 minutes before the session.

“How many times does your client have to be reminded that last-minute production is absolutely unacceptable, it is disruptive of the inquiry’s proceedings,” Commissioner John Sackar told NSW Police barrister Anders Mykkeltvedt.

“How many times has this happened? Many times, where documents have been discovered at the last minute.

“I’m sick and tired of your client’s attitude in relation to these documents and it is yet again testimony to the fact that I think your client doesn’t know where half its records are.”

The inquiry heard the documents were of “central importance” to matters to be covered on Monday, when former detective chief inspector Stewart Leggat and detective sergeant Alicia Taylor were due to give evidence.

The inquiry this week will scrutinise the case of US mathematician Scott Johnson, whose death was later ruled a homicide.

The 27-year-old died after he was punched at a gay beat on Sydney’s northern beaches and his naked body was found on rocks at North Head in December 1988.

His killer was sentenced to nine years in jail for manslaughter earlier this year.

Police initially ruled the death a suicide before family pressure, a series of inquiries and a $2 million reward sparked renewed interest in the cold case.

The inquiry, which is examining the deaths of gay people in NSW between 1970 and 2010, is due to report to the government in December.

– AAP