Let's weigh the pros and cons of each of the Perps possible Modes of transport - We have Foot, Bike, Car. We can add to the list if anyone thinks it's worthwhile.
Perp on Foot pros:
Lives very close by, likely knows area like bAck of hand. Can make quick escape to home. Has access to tools needed. Does not need to expose himself on the roadway, can travel through woods. Doesn't have to worry about HER DNA on his things (car etc). He knows neighbors and knows when no one would be at neighboring houses.
Cons:
Would likely be investigated purely based on his proximity to the crime- DNA drag net etc, has to be strong to carry out the crime, a fire could have threatened his own home, dogs may be able to track his scent, he didn't prepare the area to hide her body (this annoys me into thinking he didn't plan for long period- if all other aspects were planned it's weird that he wouldn't want to give himself more time to avoid suspicion by making her more difficult to find. He could have dug a deep hole if he could walk to this place from home, for example, MAJOR con, if he lived right there his scratches would be difficult to hide/ignore.
What else?