No, they can’t. But this isn’t the type of sequencing they do on crime dna.
They don’t have an actual Thomas Jefferson dna sample to match with so they have to use a known descendant proxy sample, using the Y chromosome because that’s the only one they can be sure was absolutely passed down.
But all the other Jefferson men who have the same grandfather have the same Y, so why it shows that some man in that family is the father it doesn’t prove which one it was. For that they would need a direct sample to do a full genome sequencing and match.
They will never get permission to dig up Thomas Jefferson.
Well, the last paragraph contains the point I am trying to make.
The concept is the same. Who did it? and the answer is analogous. We don’t know because of the shared Y chromosome. You claim it’s different. OK, but I am not seeing the difference.