BBM. You keep stating this but it's not true. You failed to produce any picture of such. I have every picture ever posted online of this family and there is not a single one of Joseph and Chase together in paintball gear.
That's not to say he didn't go with him.
@mrjitty put it so eloquently, I was thinking the same thing all morning reading posts - Chase will be perceived as a liar by this jury and they don't have to take anything he says as truth. As a juror, if you believe the defendant is lying, you can throw out and discard their entire testimony or statements made. His interview is considered his testimony of events.
If this DNA is distributed to places by secondary transfer as you suggest, why isn't it on the first places Joseph would have touched - the outside/inside door handles?