I too do not understand the neglect of the door mat. Sweat, saliva, a stray beard hair (yes they do drop out on occasion)-said this old guy with the white beard) and DNA from his shoes. All seem possible.I have listened to many podcasts on this case and heard probably over 2 dozen experts weigh in. Ex FBI, LE, etc etc.
The single thing that astounds ALL of them most is LE not taking the doormat away for further testing. Have yet to hear anyone that is not troubled by that.
They came back and took the Nest bracket after the video surfaced.....seems like that would have been the perfect opportunity to take the doormat as well. You would think.
But the unfortunate fact is-the crime scene was compromised in the first hours, and again the next day When it was released.
Heck, on that first Sunday they probably had cops, a shift commander and neighbors just trudging and driving all over the driveway. (Anyone remember pizza guy at the door?)
It reminds me of the Jon Benet Ramsey case. That went sideways at the get go.