Cthulhudrew said:
That was the marshal's case, not Kate's. Presumably he wrote "personal effects" on the envelope when he took her into custody, as a legal proceeding.
That doesn't fit the timeline, as I understand it.
1. Somehow an envelope labeled "Personal Effects" ends up in a safe deposit box, for which Kate has the key but isn't on the account. The envelope belongs to someone she (a) love, (b) killed, or (c) both.
2. She participates in a bank robbery to get into the safe deposit box. She may or may not know what is specifically contains.
3. She opens the box and sees
right then that it says "Personal Effects" on it, not later.
4. Because of the robbery and shootings, she becomes a wanted woman.
5. The marshall arrests her and puts the envelope in his case.
6. The plane they're on crashes.
As such, the marshall couldn't have written "Personal Effects" on it, that must have been someone else.
Such marking is commonly done by (a) a coroner when someone dies, or (b) a jailor, when someone is jailed.