Alexa got a bag of crematory remains so she could sift through the ashes. She laid out black plastic on the floor so that she could keep the ashes contained. She had a sieve next to the plastic which would have been useful to sift the ashes through. But she didn't use the sieve.
There was no confession from the suspect. No evidence where the murder was done, or who did it. Just evidence the victim was in the building.