I love Mexican/Texan/Cajun. When I was in Tennessee I had the most amazing catfish meal, and another cajun jambalaya concoction mmm, mmm. I even liked that restaurant chain (forget the name) of the type that we in England love to look down on. Local residents petitioned against having a MacDonalds in Hampstead, for example. Today I are be eating a Waitrose ten beans (after already having soaked and bolied them) with rice, peppers, spring onion, tomatoes and sauce, with mozarella grating.
Brits were very resistant to ID passes because of some paranoia about privacy. Biometric ID is largely voluntary in most EU countries and I can see people are resistant to fingerprinting because of the association with criminal records. But hey, it was only your index finger. As I know I will never commit a crime and being proud of my nationality, it was no problem for me. It's the same size as a credit card and my plastic drivers licence, so easier to carry around than a passport.
I would imagine police compared the palm print of several suspects. If Rudy's was already on file, I am not sure why that would be.
I expect it would be more of a "good likeness" as blood would smear any ridge points, as with the footprint on the bathmat.
I give weight to early newspaper reports as they are often folks reporting from the frontline, ground zero, before all the PR guys and lawyers come along to add "spin". It's the human fly on the wall angle. In this case, we get to see police thinking and why they were especially suspicious of Raff, who no way could claim police racism.