New South Wales prison officers who allegedly bashed an inmate then staged a cover-up were "too ready to be heavy-handed", according to a colleague who never approved of their techniques.
Wesley Duffy was one of several guards present in a cell of the Lithgow Correctional Centre when an inmate was allegedly subjected to unwarranted force in February 2014.
Appearing before a corruption inquiry in Sydney, Mr Duffy recalled warning his colleagues "that's enough" when two of them - Terrence Walker and Elliot Duncan - continued to wrestle the man, despite his acquiescence.
"Mr Duncan said something along the lines of '(if) you don't like what's going on, get out of the cell'," Mr Duffy told the NSW Independent Commission Against Corruption on Tuesday.
"They knew full well that I didn't approve of the heavy-handed techniques."
The commission is investigating allegations the officers later lied in official reports, deleted CCTV and planted drugs to justify a cell search.
Mr Duffy was a reserve member of the specially-trained response team nicknamed "the ninja turtles", but told the inquiry he preferred not to be rostered with its usual members.
"I didn't particularly like the way they operated," he said.
"They tended to be too ready to be heavy-handed."
An official report about the incident, which left the inmate with a black eye, bruising to the mouth and injured ribs, said he tripped and fell on a toilet while trying to flush contraband.
Mr Walker has admitted the report was "all lies" and also claimed Mr Duffy was excluded from the alleged collusion because other guards anticipated he would want to be honest.
Mr Duffy said he distanced himself from the group when he realised they were allegedly submitting false statements.
"I wanted no more to do with whatever the hell they were doing," he said.
Under cross examination on Tuesday, Mr Walker denied he'd been offered indemnity from prosecution in exchange for giving evidence.
"I came here just to tell the truth," Mr Walker said.
Mr Walker, who conceded he had anger issues and "quite possibly" abused inmates, was labelled as a "loose cannon" by the solicitor representing then-manager of security Brad Peebles.
But he rejected the suggestion he was implicating colleagues to preserve his own credibility, and stood by an accusation Mr Peebles at the time warned "this one will come back to bite us on the arse".
Mr Peebles was "relieved from duty" for the course of the inquiry, according to Corrective Services NSW. Until weeks ago he was one of the department's most senior officials.
The inquiry before Commissioner Stephen Rushton SC continues.