The forensic blood evidence isn't really strong IMO.
What is strong is Mark denying multiple times that Dylan bled in his house until the FBI truck arrived and he knew they would find Dylan's blood.
We the go from Dylan not bleeding to having a cold sore that dripped blood to a last gasp story about a nerf ball cutting his lip which made him spit blood on the floor. All in rapid succession.
I doubt the defense will bring that up either. JMO
Not only that the blood skipped the carpet rug but was underneath it on the floor. That’s some crafty blood right there.