Maybe he left his jacket in the RV when he left it unlocked so Danielle could sneak in, wash her hair, leave a finger print and prick herself.
Actually, The reason for her 'blood' and prints is that DW picked her up Sat morning, and since he was hung over, Danielle drove the MH around the desert, while DW sat in the back and watched PORNOS. Danielle's poor driving got them stuck out in the desert and cost DW $80. That is why he later killed her and hid the body. That is why her prints, hair, and drops of blood were in the MH.
(/sarcasm)