A previous poster said that Aimee had suddenly gone back and that they hadn't discussed it together.
This might have been me, in which case it was clumsily written on my part - I too thought they had discussed it, either in the car or just outside, and Aimee had gone back for it.
I think the handbag is one more of those things where we can all see quite clearly that it should not have happened. However, it did, and in the circumstances, I can see why they did do it. Or at least, the story that they wanted to give it to her mother makes sense, in a not-really-thinking kind of way.
I wouldn't take it. And part of me does think, did neither one of these adult people say 'the police might want to keep it, don't you think?' And that might have spurred one of them on to actually ask the question, rather than just hoping that it's OK because nobody stopped them.
It is pretty ridiculous behaviour. I wonder if it can be 'excused' by thinking that one of them had been awake since 3, and had, in that time, watched a young woman die, and the other had just found out her brother had killed a person. I'm not sure that it does. I'm just saying, perhaps this is where their sudden stupidity came from.