I know, I know, Case 3-3 is already wacky nonsense. But I've been looking around and haven't found anything about this particular detail. A friend of mine was playing through it recently and pointed out these lines of dialog:

https://i.imgur.com/8vaH8Af.png

This blood is dry...

It must have been spilled a few hours before Angie was killed. Maybe more.

That fits the 2 a.m. time of death listed in the Monokuma File.

They were in reference to this pool of blood from the first victim's neck. Was this a mistake in translation or writing? Was it supposed to be "found" instead of "killed"? Are we missing something here? Or is that really just saying that she died a few hours after being stabbed in the neck?

She did have a head wound that she received some amount of time before being killed by the neck wound, but it probably wasn't "a few hours" and Shuichi specifically says "This can't be from her forehead. This blood is from the back of her neck."