What is "this" you refer to?
In trying to decipher a crime, there are a few factors which must be weighed.
The first is known facts. Video, phone call times, text messages. Things such as these are not in doubt.
The second is implied facts. It's sunny and you are on the highway. A car drives by in the opposite direction and is wet. Then another car and it's also wet. The sky in that direction is gray. The implied fact is it's raining in that direction. It's possible both cars went through a car wash or past a sprinkler, but the solid implication is it's raining over there.
What are the known facts in this case?
Faith and her roommate came home around 3am after a night of partying at a busy club. The roommate says nobody else was there when they came home. The neighbor downstairs heard repeated sounds like a heavy bag being dropped around that same time. What did she NOT hear? Any screaming, loud thumps, violence after 4:30am, which is when the roommate left.
If Faith was raped and beaten to death after the roommate left, then why didn't the neighbor hear any sounds during that time?
Here's a key to understanding what happened. The lack of screaming. Whatever DNA was left on Faith, for whatever reason, happened after she was dead, or way beforehand. She would have been fighting and screaming for her life if she had been violated. This is why there are no charges relating to rape. The DA knows she was not sexually assaulted. This means the DNA either wound up on her prior to her coming home, or after she was dead. If it was prior to her coming home, then the DNA is not connected to any crime. As noted in a prior post, there would be lots of touch DNA on Faith since she had just come from a club. Many people would have left their touch DNA on her.
The loud thumps heard by the neighbor, consistent with multiple blows to the head, leads to the conclusion that these were the blows which left Faith dead shortly after 3am. Which is why the roommate says that she left the door unlocked. Because if she had locked it, the only logical way an intruder could enter is by breaking down the door or if Faith had made an invitation. But because the door was unlocked, an intruder would be able to walk in, commit a sexual assault, kill her, and escape undetected.
Look at the roommate's 911 call: "It looks like someone came in here. It really does. I just can’t believe this. Someone had to have been in there.”
IT REALLY DOES! She is not sure that the 911 comms person agrees, so she has to emphasize that it REALLY does look like someone came in there. This is because she REALLY wasn't there! Really!
Faith's family has/had doubts about the roommate's story.
Murdered UNC Student's Family Thinks Her Roommate Knows More Than She Is Telling