As someone mentioned in an earlier comment, dryer softener sheets can be effective tools in wiping away fingerprints.
While looking up the SDSO evidence photos I came up with a couple of questions:
1.
Why is there a used dryer sheet in the room? One of the evidence photos shows items on the floor in the mansion bedroom with the balcony. One of the items present was a used dryer sheet, lying on the floor next to the knives. What would be the purpose of having a dryer sheet in that room? Why is it lying next to the large knife?
Link to SDSO powerpoint, photo is on page 13
http://www.sdsheriff.net/coronado/rz.pdf
2. Why are there two knives and why is one of them a large, unweildly chopping knife?
If the knives were brought to the room for the purpose of cutting rope, the smaller paring knife would have been adequate for the job and easier to use. OTOH, chopping knives are usually used for chopping downward against an item while its laying on a hard surface, like a chopping block. Such a knife would be useless in trying to cut a rope, especially when the mansion kitchen likely had a large stock of good quality kitchen knives.
Since RZ was a very healthy eater, she likely knew how to use a chopping knife for cutting vegetables and fruits. If she were really planning to commit suicide by hanging, she would know that it wasn't a practical choice for cutting a rope.
OTOH, someone who might not be familiar with using a knife might choose it by mistake, or would chose it for another purpose. It's large, scary looking, etc.
Apparently SDSO never bother to follow up on these curious items. Declaring it a suicide meant they didn't have to investigate or explain.