The Hitchcock movie was called “Suspicion”
You can see it on Amazon for $2.95
Notice the ending and how it is oddly edited at the end. In this case the film had been completed and the studio ha the ending re-done.
I do not know if the Searchers ending had to be shot over but yes the original script had an ending where the girl - now a woman was murdered by Ethan. You can kind of see that coming in the movie if you watch it carefully. BTW The Searchers is one of my favorite Wayne movies and should have won an academy award. It is one of the best Westerns ever done but the original script was much darker.
The story the movie is based on is also quite dark. Cynthia Anne Parker was not able to reintegrate into Caucasian society after she was recaptured and died 10 years after being taken from the Comanches. The question could legitimately be asked if it was cruel to have recaptured her.
https://en.wikipedia.org/wiki/Cynthia_Ann_Parker
Does Grant let her slide out of the convertible and down the cliff in that ending?