^ Yes, December -- the lid was on top when the body was found; it was specified on the autopsy report that 2Hip2BeSquare and others possess. 2Hip summarized the report beautifully somewhere, but I can't remember which thread (I wish we can get a separate thread with just that summation -- it was very good, even though she/he didn't include everything).
I'm really intrigued by the lid and I love how you bought up how you thought it wasn't attached. I found the photo you were referring to, but in my opinion, I'm not satisfied by that photo that it wasn't attached. I'm not satisfied for the following reasons:
If the hatch on Elisa's tank was indeed different than the hatch of the tank in front of it, it would mean that it was a top cover. Since the edges of the opening clearly aren't bevelled, that would mean that the top cover would've had to be bigger in circumference and fit around the edges of the opening. To me, if it was an unattached top cover, the opening would've had to have bevelled edges to fit a top cover, ensuring that it wouldn't blow away. It just seems odd that it would the other kind of top-cover, considering LA has earthquakes and storms, that could easily dislodge a cover like that.