A firearms officer at the Metropolitan Police is the subject of a homicide investigation over the fatal shooting of soon-to-be father Chris Kaba.
Mr Kaba died in hospital in the early hours of Tuesday morning after being shot following a chase with police on Monday night in Streatham Hill, south London.
The police watchdog, which is investigating the incident, said a single round had been fired by armed officers.
In a statement, the Met's assistant commissioner Amanda Pearson confirmed: "The Independent Office for Police Conduct (IOPC) have announced that a firearms officer is now subject to a homicide investigation.
"My thoughts and sympathies remain with Mr Kaba's friends and family with this news. I also know how concerned our communities are and how they will also be affected by this significant update. We share their concern.
"The Met is co-operating fully as the IOPC work to independently establish the full circumstances surrounding the shooting."
The officer is not currently on operational duties due to the "formal post incident process", the statement added.
"A senior officer will now carefully consider their work status going forward," it said.
'A baby that he's never going to see'
Mr Kaba's car was stopped, the force said, following the activation of an automatic number plate recognition camera, which indicated the car had been "linked to a firearms offence in the previous days".
His family called for a murder investigation after it emerged no firearm was found on him.
Kim Alleyne, whose daughter Karimah Waite was engaged to Mr Kaba and carrying his child, said the pair were due to marry early next year.
She said: "He was so loved. He was so funny. He was super kind.
"He's got a baby on the way that he's never going to see."
Mayor of London Sadiq Khan said the IOPC's investigation was a "significant development".
"I fully understand the grave concerns and impact of Chris' death on black Londoners across our city and the anger, pain and fear it has caused - as well as the desire for justice and change," he said.
"I appreciate that there are many unanswered questions and I want to reassure all of London's communities that I will continue to push for these to be answered."
The IOPC stressed this development does not mean any criminal offence is proven at this point.
"We continue to ask that people avoid speculating about this incident out of respect for Mr Kaba's family and for everyone else affected," the watchdog said.