Well there’s the insulin poisoning
and also there’s coincidence
but there’s a coincidence and then there’s too many coincidences
Police combed over all of the rotas, etc before she was arrested. And they had to get the green light to arrest and prosecute her.
If there was other evidence pointing to someone else then there case means absolutely nothing
However if there was another person present for the majority of situations then im sure they would have been looked at closely. This is not a case that the police want to bring or even anyone wants to think could even happen