A NSW prisoner who claimed he had nothing to do with the bashing of a fellow inmate has been found guilty of the man's murder.
Abraham Ryan Tangi, 31, was on Thursday found guilty of the murder of Zaydoun Al-Qaseer by a NSW Supreme Court jury.
The two men had been awaiting trial for separate matters when they were both filmed entering a cell at John Moroney Correctional Complex near Windsor in June 2017.
Only Tangi emerged before prison staff found Al-Qaseer lying on the floor, unconscious and bleeding.
An inmate had testified he saw Tangi stomping on Al-Qaseer's head.
Tangi's barrister Gabriel Wendler later characterised the witness as "an unashamed liar" who must have had a special ability to see around corners.
He also attacked the credibility of other witnesses on the basis they had "a deeply embedded dishonest nature", were "totally unreliable" and made up "a false and magical story".
"It is my submission in relation to the inmate witnesses, you would not accept their evidence unless it was supported by independent witnesses – it is not," Mr Wendler told the jury.
The victim's injuries included a fractured skull, bleeding in the brain, a broken collarbone and bruising on each side of his head and on his shoulder.
The jury heard the evidence showed only two people were in cell 24 at the relevant time.
"No one else went in until after the point in time when Abraham Tangi came out and that, at that point in time, Zaydoun Al-Qaseer had already suffered the injuries that led to his death," prosecutor Philip Hogan said.
Tangi told police the men had been in the cell alone together, but Mr Al-Qaseer was uninjured when he left.
Tangi will be sentenced by Justice Stephen Rothman at a later date.