I read a similar article in the Guardian today, to sum it up.
The DNA on the bra was dust...which considering Solletico was in the apartment a lot, dust flies in the air, landed on clothing on the floor is not out of the realm of imagination. and yes, DUST, not blood, not sweat, not semen, not hair DNA, but DUST.
The knife one is interesting too, NO DNA found and when the police went to search his apartment, they took just 2 knifes out of the entire drawer? If you suspect the killer hid a knife, you would take EVERY SINGLE ONE? and do test on them all? Nooooo, they took 2 out of the entire kitchen and left the rest.
The more you read into it, the more it reads like the police just wanted to frame these two.