The Metropolitan Police has commissioned an independent review into how it responds to people with mental health conditions.
A panel will examine every case during the last five years where someone with a mental health condition has either died or been seriously injured after police contact.
It follows criticism over the Met's actions prior to the deaths in custody of Olaseni Lewis and Sean Rigg.
Both men had suffered mental illness.
Olaseni Lewis, known as Seni, was a 23-year-old IT graduate with a degree from Kingston University who had planned to undertake postgraduate study.
He died in 2010 after collapsing during prolonged restraint by police.
Mr Rigg, 40, died at Brixton Police Station in 2008. An inquest found police used "unsuitable" force.
After his inquest, a report by police watchdog the Independent Police Complaints Commission (IPCC) said: "Sean Rigg's death is a symptom of a deeper problem: the linkage between mental illness and deaths in or following police custody."
The commission will be led by Lord Adebowale, chief executive of the social enterprise Turning Point.
'Clarity of focus'
Call handling and custody procedures will be examined, in addition to the Met's relationship with other organisations such as the London Ambulance Service while dealing with mentally ill people.
The families of mentally ill people who have died after encountering the police are being invited to contribute.
Commissioner Bernard Hogan-Howe said: "A number of cases have highlighted concerns with how police respond to people with mental health conditions.
"I want to know that we are doing everything we can to get this right.
"That is why I've commissioned this independent review."
Lord Adebowale said: "I welcome the commissioner's commitment to improve practice in this area.
"What is important is to get to the truth of the matter and remove any excuses for not taking the chance to improve practice.
"I enter this review, careful to have an open mind, with clarity of focus and to be driven by the facts."
The commission's recommendations will be presented to the Met in February 2013. Its report will then be made public.