Does this qualify as stealing

So a few matches ago, a player who I was bot-laning with repeatedly got mad at me for kill-stealing. So much so, that he quit the match. ( He came back like ten minutes later, but still. ) Here's the thing though. Whenever I "stole" a kill from him, he was already dead. Example: He goes in to fight an enemy he can't beat, get's them to about half health and dies, then I come in about six seconds later and kill them while he's still respawning. Kill-stealing refers to robbing someone of their obvious win. But unless you're teemo (he wasn't by the way) you can't kill from the dead. So, was I still technically stealing?