Flores knew Zach housesat on June 2- he wrote just that in his earlier investigative report. I think he was trying to trip up the killer/figure out a timeline/find out what she knew about his roommates' schedules.
Reviewed, in context: I think Enrique was remembering June 2, and pretty accurately, just one day off. When reinterviewed Zach was one day off with some memories, but clearer about the 4th.
The killer had to have known Zach was there when she arrived, because his rental was parked in the driveway. Enrique didn't have a car and she had no way of knowing he was there, IMO. I think she sent the text on June 3AM about the room to find out if TA had a second roommate yet. Travis didn't reply. She didn't know.
Enrique left at 6AM. If she looked out into the driveway after he left, she knew that Zach - or someone in the house- was still there. Zach was driving a rental car, so it's possible she wasn't even sure if Zach was still TA's roomie or if T had another new roommate.
(For that matter, when she saw an unidentifiable car parked in the driveway, how could she have been sure TA didn't have a GF over for the night? Unless she snooped into his window first, while he was still awake, and saw him alone? Or after he was asleep, looked into his room to make sure he was alone?)
Either way, she couldn't be sure of the unknown roomie's schedule, nor of when Enrique might return. That's a lot of uncertainty for timing a murder....
In any case, Zach did get up and leave in the AM to return his rental car, before returning at 3. So she had to have dodged not one but TWO roommates morning/early afternoon, then Zach no doubt unexpectedly returning from 3-4.
As far as the floor cleaner. It was there when Enrique returned on the 4th, between 6-6:30, the furniture was moved, and the stair bannisters were slick.
Zach says he too noticed the cleaner, furniture moved, and slick bannisters when he returned on the 4th. What isn't clear is if Zach was referring to his first return at 3pm or his return later that evening, after Enrique's return.
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And that IS that for my own sleuthing of the killer. Can't wait for JM's book to arrive in my mail!!!