there was earlier speculation by some posters questioning if the LL actually saw Lucas and if Lucas was actually gone much longer. maybe what wasnt sitting well for some people isnt the question of the LL's sighting but the timeline. maybe weve been looking at it backwards.
speculating this was all done fri night, why would she dispose of the body so quickly? and why would she call him missing so soon instead of take the time to come up w the perfect coverup? she could prob stretch it to 5 days if needed. the other parent of the household is gone, she is telling the school Lucas is sick, has access to DR notes somehow and a limited social circle (and w friends you could be like dont come over/her friends prob are more of a dont ask question crowd).
lets say the LL came by and left her a message (text or voicemail) saying "hey i came by, looks like you arent available but ill be back first thing monday morning, maybe over the weekend if i have time". maybe he also says in his voicemail "looks like you are here bc your son is here but you arent answering your door" or maybe Lucas tells her he saw the LL. lets even say its about the cat so she knows the LL is checking in on her and already unhappy w her as a tenant. later when she gets back from OG and Lucas passes she has an "oh crap" moment, i have to dispose of his body and clean immediately because:
1. someone is coming by the house and i cant refuse them entry since hes my LL. also, if anyone were to notice a weird smell/somethingoff, it would be the LL since he just cleaned/inspected this house
2. while she could make up an excuse why Lucas wasnt home, maybe she didnt want to give the LL more reasons to be suspicious of her (maybe she was worried he noticed Lucas' bruising in the window or maybe Lucas peeking out the window wouldnt seem so innocuous to the LL if more suspicious circumstances popped up). so it was better to get ahead of inevitable situation and fast.