The lack of any CCTV images is a setback for investigators probing the death of 27-year-old Lyji Vaggs in Townsville Hospital last week, and will dismay relatives who say the response by security men and police was heavy-handed.

At the request of Mr Vaggs's family, an independent autopsy on his body was performed in Cairns yesterday. The family is expecting to receive preliminary results as early as today.

The circumstances of his death, documented extensively by The Australian, are being examined by the Queensland Coroner and the ethical standards division of the state police.

Mr Vaggs's aunt, Gracelyn Smallwood, a prominent Aboriginal health academic and activist, said yesterday the family did not accept police assurances he was not Tasered during the hospital confrontation.

The father of three went to Townsville Hospital last Wednesday on the advice of a mental health assessment team that saw him at his Mundingburra home.

This followed unsuccessful attempts by Mr Vaggs to be admitted for treatment for a bipolar condition and schizophrenia, which was causing to him "hear voices", according to relatives.

After being told there was no room for him, Mr Vaggs is said to have become agitated in the reception area of the mental health unit. Security staff and police were called to restrain him.

According to the family, witnesses saw him being sat on and laid upon by up to six security officers or hospital orderlies, before he was handcuffed by police.

Associate Professor Smallwood said the family was told by the intensive care consultant who treated Mr Vaggs that doctors were at a loss to understand how he had lapsed into respiratory failure after being sedated. She said the consultant had said it was "probably because of the restraints".

Queensland police yesterday insisted Mr Vaggs was not Tasered with a stun gun but refused to say whether he had been handcuffed, because the case was before the coroner. The hospital management did not return calls.

Mr Vaggs's family had been pinning their hopes for an early explanation of what happened on the CCTV that is supposed to cover public areas of the hospital.

However, The Australian has confirmed that the hospital told police no such footage exists.

It is not clear whether the system was inoperative at the time, or if the cameras did not cover the area where the drama occurred.

Mr Vaggs's mother switched off his life support 24 hours later after being told by doctors her son had suffered massive and irreversible brain damage.

The family wants to know why the hospital did not call an indigenous person or Mr Vaggs's relatives to help calm him.