The public appearance came following the release of an image of Mr Arwani on Saturday April 11, along with a photo of the make of the car where he was found slumped at the wheel.
The 48-year-old, a father-of-six, who had served as an Imam in an Acton mosque was found shot in the chest in a dark coloured Volkswagen Passat in Greenhill, Wembley, on Tuesday April 7.
Detectives have established Mr Arwani had driven near to the scene around mid-morning on Sunday April 5, and had been parked up in Havenwood where he remained for a short while.
Officers are appealing to anyone who was in the area on Sunday April 5 or Tuesday April 7.
They are particularly keen to speak to anyone who may have seen Mr Arwani or his car.
He said: "The police are currently investigating this brutal murder. As an individual, a family and a community, we are helping the police to solve this heinous crime.
"Any information we have has, and will be passed on to them and we urge anyone with any information to please please please do the same.
"To members of the public that knew my late father and even those of you who didn't know him, please tell us what you know.
"We know that it won't bring our father back to us but it may help to deliver justice to those who killed him."
A post-mortem gave the cause of death as gun shot wounds.
The precise cause of death is yet to be determined by the coroner.
An inquest is to be opened and adjourned at Barnet Coroners Court in the coming days.