There must be direct proof of death as by finding and identification of the body of the one supposed to be murdered.
"The Eye of Dread"
Payne Erskine
3. identification of Stars Only the brighter stars can be used in navigation.
"Lectures in Navigation"
Ernest Gallaudet Draper
And when Min suggested we turn the girl over to the Missing Robots Bureau, I reminded her the mech's identification had been filed off and it might take years to trace her.
"The Love of Frank Nineteen"
David Carpenter Knight