Well I don't know precisely what MLT PD is thinking, I did previously post 3 suicide scenarios that fit the same timeline. Just search in this thread, I am too lazy to make a link. The first scenario is totally pre-planned suicide (i.e. every step was deliberate, the text message to co-workers to explain not meeting them, cutting fingers to leave blood stains, turning the phone off, leaving the car, walking to the culvert, entering it with the bag on her head. The 2nd scenario was basically panic i.e. failed attempt with razor (found she couldn't make herself cut deeply enough or felt it might take too long), abandoning the car, looking for somewhere to end her life, stumbling across the culvert. The 3rd was some kind of medical event (sudden onset dementia or whatever) leading to confusion, disorientation and what is effectively an accidental death in the culvert.
My assumption is she put the bag over her head, tied it as best she could around her neck, then laid down in the water and waited to succumb. (We just had a drowning suicide --- no weights, no bag, knew how to swim - explain that?!) Despondent people can definitely will themselves to do things you or I would ordinarily have trouble doing. They can also attain a state of calm enough to let what is going to happen, happen. They can also simultaneously plan to kill themselves while feeding the dog, paying rent, and booking a vacation or whatever.
There's no real evidence I'm aware of that would support any one of these scenarios vs the others.
My gut tells me somewhere between the 1st and 2nd scenario because nothing to support a medical event came up in the autopsy though they can't detect everything. I would also say the culvert looks "attractive" for suicide. One might think it also would for dumping a body, but it isn't. Too near the road, though the water is a big plus to wash DNA away, but criminals aren't that smart usually. If I were dumping a body there, I'd go for the wooded area near it.
