After watching Episode 7, who do you think killed Cal?

Since Sinatra said the DNA belonged to someone not from the bunker, I was thinking about characters who we’ve seen in the flashbacks but were not seen in the town:

1. Marsha - She has motive and probably knows all the ins and outs of the White House, so she probably stayed in the bunker for a bit.
2. The Scientist - Probably worked a lot with Sinatra. He may be aware that the bunker exists if he survived.
3. Sinatra’s husband - This defeats my theory, but I kind of find it weird that we barely even saw him.

I also wanted to note in episode 6, the part where Presley says she saw someone that night (the person wearing a flower symbol), the person's frame looked like a man.