Blood was discovered in the trunk and passenger compartment of the vehicle Rowland was driving, police say. The blood was later confirmed to be that of Josephson by SLED.
Nathaniel Rowland: What we know about suspect in USC student Samantha Josephson homicide
I think it is easy to imagine this car interior covered in a horror show of blood, but the reality is likely that NR did clean it up, just not under the carpets or in the cracks, and the luminol will light it all up anyway. So, his female passenger may not have seen or suspected anything (especially at night).
Perhaps this was a robbery and he used something in the car as a weapon when Sami fought him. Or perhaps it truly was a stalking with intent to kill. The kind of rage I attribute to NR is not short - it brews for years and years until the need to alleviate it overcomes all else.
This made me laugh. In all seriousness, I think he is self-employed, going by what we know of him.