It's foolish for a state actor leave the remnant pieces of an advanced weapon (like an autonomous drone) at the scene of a crime during an assassination. First

It's foolish for a state actor leave the remnant pieces of an advanced weapon (like an autonomous drone) at the scene of a crime during an assassination. First because the uniqueness of the technology makes the actor identifiable, second because the country targeted will react more cohesively to this novel kind of cassus belli (e.g. news coverage of 1 drunk driving death vs 1 autonomous vehicle death) The good old fashion alternative is just a gunman. It's more plausibly deniable - e.g. still nobody is exactly sure what was going on with Lee Harvey Oswold and Jack Ruby - and it doesn't put the targeted country immediately on a war footing.