Reminds me of a scene in The Town - they were going to rob a bank, and they collected whole bags of hair from a barbershop floor, and spread it during the robbery.
They may be able to pinpoint a location - the barber where all the DNA matches go to have a haircut, and a time - soon after all those with majority DNA in the pile of hair went to the Barber's. Then they can analyse who was in the area around the time and find a person involved.
Can you point to current DNA tech which doesn't destroy the sample while processing it?
https://www.nytimes.com/2019/09/16/science/hair-dna-murder.h...