The video shows officers forcefully restricted Jozef Chovanec's movements in a cell at Charleroi airport, with one officer sitting on him for a long time. Another officer made an apparent Nazi salute during the incident.
Duesseldorf police said in a statement that a video of the incident is "being intensively analysed and evaluated with regard to how the police intervened."
Cedric Chouviat, 42, died after being pinned to the ground by arresting officers. Video footage of the arrest reveal he said "I'm suffocating" at least seven times.
The tiny Marxist-Leninist Party of Germany erected the first statue of Lenin ever on former West German territory.
"We are fighting wickedness in high places," said civil rights leader Al Sharpton in his eulogy at George Floyd's funeral.