When she went back to the same PetCo to alibi herself after two hours, how does this provide an alibi? To me, it just tells me at those two specific times we know where she was. We do not know if Gannon was with her on either visit.
The whole Petco story is coming from TS at this point, so until LE releases info verifying any such trip(s), I'm questioning whether and/or how many even occurred.
Having said that, IF TS went to Petco on Monday, we can be confident that her reasons for doing so were both convoluted and stupid.
If she went to Petco, the store receipts and security cameras will tell the tale.
I'm confident LE has pieced together her purpose in making that stop (or stops).
Trying to "think" like TS, one thing that occurred to me as being one possibility is that she purchased something there she needed to help her carry out her murder plot.
It may have occurred to her after the fact that LE might ask her to show them the items she'd purchased there that day.
She then may have decided she needed to go back to Petco to replicate that original purchase, just in case. That way, she'd be able to furnish the items listed on the original receipt if LE asked about them. TS may even have paid cash on the second store trip (if there even WAS a 2nd trip) to avoid duplicate charges showing up on her statement.
That above entire scenario is both horribly convoluted and incredibly stupid, which is precisely why I can easily envision her doing something like that.
It sounds exactly like something Frazee would do, given the same situation.
JMO.