Additional medical tests, including determining if Alonzo Ashley, 29, had drugs in his system, will take about six weeks to complete, said Chief Investigator Donald Bell of the Office of the Medical Examiner.

Investigators also want to review any video that might have been taken of the Monday afternoon confrontation between Ashley, police and zoo security guards outside the elephant house, Bell said.

Police said that Ashley continued to violently resist as officers attempted him to restrain him. Officers were called by zoo security guards who said Ashley attacked them when they tried to intervene in a domestic violence dispute between the man and his girlfriend.

Ashley's girlfriend told 7NEWS Tuesday that he had not been violent with her.

She said Ashley was dehydrated on a hot day, and when his put his head under a fountain to cool off, security guards told him to stop.

The girlfriend said when security guards started asking her questions, Ashley grew combative, saying, "You want to fight?" The girlfriend did not want her name used.

Police said Ashley spun out of control, hitting one officer and biting another. Police said a zoo employee was also bitten and suffered a head injury.

Officers attempted to use a Taser to subdue Ashley, but police said the stun gun had no affect.

After several minutes of fighting, police said they had Ashley in custody. Ashley then started convulsing and stopped breathing.

Officers and paramedics attempted life-saving measures, but Ashley died at a hospital.

Police said they found drugs and drug paraphernalia on Ashley, but a police spokesman would not specify the type of drugs.

7NEWS checked Ashley's criminal background and found he pleaded guilty to possessing drug paraphernalia in 2003.