er.. no manslaughter is the correct charge. Assault resulting in death is manslaughter.
What I'm wondering is (as the family have said they're bringing a civil case), as the Met failed to vet the guy properly and therefore are responsible thru their own admission of putting a dangerous and violent officer on the streets, if they can bring a corporate manslaughter (or similar charge) against the Met as well.
I really don't get the law with civil cases, they're odd and lead only to financial compensation as far as I understand it (poorly) and never any custodial sentence.