He could have worn gloves.
How do we know he didn't leave anything at all behind? Something could have been missed.
I don't know these things, I'm just saying they are possibilities.
He probably did have gloves. It was freezing outside. But wouldn't he have taken them off to handle JonBenet? Or to write the ransom note?
He would have had to wrap himself in saran wrap....not to leave evidence......but then again...there was a house full of people in the house by the time the police started to search for evidence...the whole house was contaminated by then...