An object removed from the throat of a black man who died after a police chase "did not contain a controlled substance", according to forensic analysis.
Unverified footage on social media appeared to show at least one police officer attempting to restrain Rashan Charles, 20, on the floor of a shop in east London before he died later in hospital on July 22.
His death sparked violent clashes with police in Hackney on Friday as demonstrators hurled bottles and fireworks at officers.
The Independent Police Complaints Commission (IPCC) watchdog, which is investigating the events leading to the death of Mr Charles, said: "The IPCC has now received results of forensic analysis of an object that was removed from Rashan's airway by paramedics.
"The object did not contain a controlled substance."
The IPCC said its investigation into the circumstances of Mr Charles's death following contact with police in Hackney is "ongoing and making good progress", adding: "Our independent investigation is thoroughly examining all aspects of police interaction with Rashan prior to his death and has already undertaken a large number of investigative actions."
The watchdog said IPCC staff met with Mr Charles's family on Wednesday afternoon to update them with the results of the forensic analysis.
Mr Charles's family made a fresh plea for "peace on the streets" at the weekend following the violent clashes.
Demonstrators blocked Kingsland Road in Hackney with wheelie bins, mattresses and debris on Friday afternoon - with bottles and fireworks later being thrown at officers as the growing anger bubbled over into the night.
Outside Stoke Newington police station on Saturday, his father Esa gathered with the family of Edson Da Costa - who died last month, six days after being detained by police - for a vigil organised by Stand Up To Racism.
Stafford Scott, who stood next to Mr Charles and spoke on behalf of the family, directly addressed the young people who protested the night before, and said that they understand their anger and frustration.
"Don't feel that the family don't feel that anger and that frustration too. But what the family knows is that taking it to the streets doesn't give you justice," he said.
Mr Scott said the family have found the best legal support they can and are now asking the community to "support them in their struggle" but with "peace on the streets".
Those in the crowd at the vigil could be heard chanting "no justice, no peace" as they called for the police officer who arrested Mr Charles to be suspended.
Last week, the IPCC said the evidence it had seen so far suggested that Mr Charles was detained by a Metropolitan Police officer who had followed him on foot into a shop on Kingsland Road after an earlier attempted vehicle stop.
The officer restrained Mr Charles, with the help of a member of the public, and he was handcuffed.
After he was detained, attempts were made to remove an object from his mouth or throat.
His condition deteriorated, and the officer called for a police medic who provided assistance prior to the arrival of paramedics, according to the IPCC.