There hasn't been anything mentioning head injury. If Cheryl fell in that culvert, she should have some head injury due to the concrete! Or all the rocks visible in photos have shared.
Nope, still not seeing suicide.
As for the razor blade. There is actually a comb that has a razor blade in it for removing matted fur. I own two of them. The razor blade has to be changed because they get dull, and thus pull and hurt the animal when trying to remove a mat. Something you don't want! So want the blade sharp, and sliding easily through the mat. Often the mats will contain dirt, or flea dander in it, and further dulls the blades. *I have a Great Pyrenees this happens to A LOT* Scissors scare him, the electric or rechargeable clippers scare him, so I use that comb with the razor blade, especially during Spring shedding season!
You can buy the single blade razors in bulk, and they contain a small piece of thin cardboard covering the blade. In water, that part would fall off the blade.
I've been known to wear the same pair of pants two days in a row. If I had been doing something, and placed a used blade in my pants pocket, it would be there the next day.
I didn't have the pleasure of knowing Cheryl. So I have no idea what her lifestyle was like, or if it was familiar to my own in any way.
Like any case, we all have biases based on our own life experiences.
As a fellow animal rescuer, fostering the ones deemed not suitable for most homes, and a huge love for animals, I can't imagine anyone I know, or anyone that I have been associated with committing suicide with no plans for the animals, nor after waiting months to get an animal, and then suicide 2 days later. Doesn't add up. I will admit that burnout is high in the rescue world, but it doesn't seem Cheryl was doing rescue at the rate that people burn out. She wasn't a vet, another profession that has a high suicide rate.
I would rather think someone had committed suicide versus homicide. But I'm not seeing it in this case.