At 41:25 in the clip below Chris Watts tries to imply that Shan’ann was with the kids “last night”. Then he corrects himself, telling Coonrod he was with the kids all weekends. He hastily throws in an alibi, while he’s at it: he took them to a birthday party Sunday.
During my initial research into the case, before information emerged about the birthday party, I thought it was possible the children had been killed on Saturday, or even earlier. This shows the importance not only of the party, but Watts taking photos at the party showing evidence of them being alive and him looking after them and entertaining them.
Also worth watching, at 40:43 Coonrod asks Watts if his kids take any medication. If Watts used 80mg Oxycodone to drug and kill his daughters, this question should have made him nervous. Does he look nervous?
Notice also how he role plays reaching for the neck area while describing the pharmacodynamics of the active ingredients…