The IOPC is appealing for information or any video footage from members of the public or from nearby properties, boats and barges.
The police watchdog has urged the public not to speculate about Kelly’s death.
Amanda Rowe, IOPC director of engagement, said: “Our thoughts are with the family and loved ones of Karnell Kelly and everyone affected by his death.
“We need to independently establish the exact circumstances of this incident given that he has died following an interaction with police officers.”
Officers made more than 600 arrests during Notting Hill Carnival over the weekend, the Met said.
Hundreds of thousands of revellers attended the event in west London over the weekend, and people in costumes and steel bands moved through the streets as the carnival celebrated its 60th anniversary.
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