Statistically. I think your first option is far more probable. Most, and perhaps even a significant majority of criminals commit crimes (both horrendous and mundane) in areas that they are familiar with and thus are comfortable in. In this case, the perpetrator was in a relatively obscure park, felt comfortable on a high bridge, comfortable crossing a creek, and apparently also knew the unmarked shortcuts into and out of the area. Though none of this knowledge is secret or highly specialized, I think the totality of it loudly says: "local" or "former local". Then factor in that his clothes and personal appearance are neat and non transient like and that the area does not appear be a popular stop with transients.