He had been arrested in Syria 48 hours after arriving in the country for humanitarian work last November.
His body had been transferred from Syria to neighbouring Lebanon on Saturday where his mother Fatima and brother Afroze received it.
Another autopsy will be conducted in Britain.
A Metropolitan Police spokesperson said its Counter Terrorism Command was providing family liaison support and would "seek to assist the coroner when appropriate".
Khan went to Syria last year to work in a field hospital in a rebel-controlled area.
The doctor who worked at the Royal National Orthopaedic Hospital (RNOH) in north-west London had entered Syria without a visa after bring moved by the plight of refugees and worked in camps in Turkey, his family said.
The UK Foreign Office said the doctor had been "in effect murdered" by the Syrian authorities and at best his death was "extremely suspicious".
His distraught mother, however, blames herself.
"I killed my son," Fatima Khan said sadly last week, as she sat in a hotel room in Beirut.
"My children kept saying to me, `Leave it alone`, but I wouldn`t listen. The trouble is, I made him seem more important than he was. [The Syrian regime] knew what he had seen and heard, so they could not let him out alive.
I ruined everything. That`s why he`s dead. All I want to do now is lie in the same grave as my son," she added.
The Syrian government claims Khan hanged himself in his cell in Damascus last Monday, using his pyjamas as a noose - four days before he was due to be released.