Kingsley Burrell death: March to police HQ, Birmingham
A march is taking place in Birmingham city centre in memory of a man who died after being detained by West Midlands Police.
Kingsley Burrell, 29, was detained under the Mental Health Act on 27 March after officers attended an incident in Icknield Port Road, Birmingham.
He was admitted to a unit in the city and later moved to a hospital where he died four days later, police said.
The Independent Police Complaints Commission (IPCC) is investigating.
Mr Burrell's sister Kadisha Brown Burrell, who will be at the march, told BBC News that they did not know how he died.
"We have never been told what the cause of death is," she said.
"We have been told the [IPCC] investigation will take about six months and we get updates from the coroner but the inquest has not happened yet."
In a statement issued shortly after Mr Burrell's death, police said that three days after he was detained under the Mental Health Act officers were called to support medical staff at a mental health unit following reports of a disturbance.
Mr Burrell was transferred to hospital but died the following day, the statement said.
Ms Brown Burrell said she expected about 2,000 people to attend the march, which started in Abbey Road, Hockley, at about 1200 BST.
"It's to demonstrate the heartfelt bereavement the whole family and community have been suffering since my brother's tragic death.
"Basically, his family - indeed, the entire community - are outraged by his tragic and unnecessary death so we need to know how and why he died."
The march ends at West Midlands Police headquarters at Lloyd House in the city centre.
A police spokesman said the force was aware of the gathering.
"We are aware of a procession planned for Saturday 2 July.
"As members of the multi-agency safety advisory group which approve such events, we have been working with partners and the organisers to ensure a safe procession."
The force has said it supports the IPCC investigation and "does not underestimate the impact this incident has had" on relatives and the community.