A man who died after a police chase in London had a package in his throat containing "a mixture of paracetamol and caffeine", investigators have said.
Rashan Charles was followed by officers in Dalston on 22 July and became ill after putting an object in his mouth.
In a statement, the Independent Police Complaints Commission (IPCC) said the package was "wrapped in plastic".
Commissioner Cindy Butts added the police watchdog had not yet been given a confirmed cause of death.
Mr Charles' death sparked a number of protests in east London, including one which turned violent.
Ms Butts said the IPCC had decided to release information about what was in the package "given the inflammatory nature of some ongoing speculation".
Last week the police watchdog said the evidence it had seen so far suggested the 20-year-old had been followed by a police officer into a shop on Kingsland Road.
The officer then restrained Mr Charles and attempts were made to remove an object from his mouth or throat.
'Disproportionate use of force'
His condition later deteriorated and a police medic was called to provide assistance before paramedics arrived.
Ms Butts said the IPCC echoed the family's appeal for calm after a wave of angry protests and violent clashes amid accusations of alleged police brutality.
The police watchdog's announcement came after shadow home secretary Diane Abbott said the initial forensic findings would cause "deep concern" after figures showed a "disproportionate" use of force against minority groups by police.
On Tuesday figures released for the first time showed Metropolitan Police officers used "force" at a rate of around once every 10 minutes.
There were 12,605 incidents of force against people by individual officers registered in the three months to the end of June.
The data showed 45% of the individuals subject to force were white, 36% black and 10% from the Asian community.