My own thoughts on HH and the events around CO exit, based somewhat on what others have brought up here that make sense to me. She did the interview and then they drove back to the hotel in both vehicles. TS comes up with an excuse to go out later, needs to borrow aunt's rental quick. She gets GS, loads him in the back of the van, which no one will be checking inside again. On the 1st, aunt and HH fly out to SC, returning the car. TS is driving solo with the van.
In that scenario, HH would still not know anything other than her mother's narrative, and because the RD video comes out later, it'd make sense that they stick together up until that video release. After the video, TS has likely already dumped GS in FL and back in SC with HH. Maybe being out of CO made it difficult for investigators to even get ahold of HH, so her unwillingness to answer questions the first few days is a little more understandable. On one hand you want to help find your bro, on the other you have your crazy mom saying the blues are out to get *them*. In the weeks following the video until the arrest, maybe HH wasn't able to be contacted again, or she didn't have their number, or they just moved on and didn't feel the need to re-engage with her so the "uncooperative" aspect is just carried thru. Did LE have any idea where HH was for the few weeks after they left CO?
Anyway, that's all I can come up with and still not get too riled about the wording in the AA about HH. I feel less inclined to defend her knowing she didn't actively help LE early in during the investigation. Of course, after the video was out, the weeks of SM discussions/news stories, and after the arrest of her mother, if her stance was to still not talk to LE about anything then I'd feel even less sympathetic towards her. But there's also a chance that LE and HH never even crossed paths again after the 31st.
