Detectives are still working to establish what caused the death of a man after the Finsbury Park Mosque attack, the head of the Metropolitan Police has said.
Commissioner Cressida Dick said a special post-mortem examination had been carried out to determine why Makram Ali, 51, died, as Scotland Yard continued to question attack suspect Darren Osborne, 47.
Mr Ali had already been taken ill when a van was driven at him and a group of people giving him first aid.
He was pronounced dead at the scene and paramedics took nine people to three London hospitals while two others were treated for minor injuries.
Speaking to the London Assembly's Police and Crime Committee, Ms Dick said: "We continue our investigation to establish exactly how he came to his death.
"We have carried out a special post-mortem and we are working very closely with his family and with all the people who were affected, and their families."
Osborne, from Cardiff, has been arrested on suspicion of commission, preparation or instigation of terrorism, including murder and attempted murder.
Detectives have been granted a warrant to hold him until 12.54am on Saturday.
The father-of-four was described by relatives as having been "troubled for a long time".
In a statement, his family said: "We are massively shocked. It's unbelievable. It still hasn't really sunk in.
"We are devastated for the families. Our hearts go out to the people who have been injured."
They said Osborne was "not a racist" and had never expressed racist views, adding: "It's madness. It is obviously sheer madness."
A man living near Osborne said he reported him to police for sleeping "drunk" in a van 24 hours before the rampage.
Edward Gardiner, 28, called officers when he saw a man smelling of alcohol asleep in the vehicle with the door open.
He believes it was Osborne.
The vehicle Mr Gardiner saw was rented from Pontyclun Van Hire, near Cardiff, the firm which supplied the one used in the attack.
Mr Gardiner, a self-employed builder and plumber from Pentwyn, east Cardiff, called police at 12.27am on Sunday.
"I could smell alcohol on him and he was grunting and groaning. I poked him but he didn't respond so I called 101," he said.
"I thought it was some random drunk guy who wanted to pull over to have a kip. I thought someone should go and check on him.
"I didn't think anything about it but then I saw the news reports and it was the same guy, the same van."
South Wales Police said no offences had been committed when they went to the street in the Llanedeyrn/Pentwyn area of Cardiff.
A spokesman said: "A male was asleep inside the vehicle, which showed no signs of having been driven recently.
"The officers' assessment was that no offences were disclosed."
NHS England said that four patients are still receiving care at two London hospitals - two of them are in critical care at the Royal London.