Git. How to find out who deleted a branch in origin?

Question

git

Hello,
actually a subject. There is a local branch prep. she was looking at the origin/prep branch.
And then, during the git pull, it turned out that origin / prep does not exist. It was most likely merged into the master, after which it was removed.
Wang, that you need to look at the reflog, but it's not strong at all.
What commands can be used to find the moment of this removal? and how to find out who deleted it?
Thank you!

Answer 1

in the Gita in no way
only by accompanying signs - ssh sessions, etc.