I'm familiar with Sycamore Canyon. It is about 2 1/2 hours north of Phoenix,between Prescott and Sedona. There is a good unpaved road that leads to a parking area. A flat, well traveled trail follows the creek in a deep Canyon. The hiking to the Blue Hole, 2 1/2 miles up the canyon , is easy. A fit woman in tennis shoes would have no problems, even if she we 9 months pregnant.
Going up the side of the canyon is another matter. I had no idea where she was found, but the canyon walls are not entirely impassible. One can work their way up, climbing hand and foot while working your way laterally to find a passable route. This is, however, very risky because it is easier to climb uphill than down and it is often difficult to retrace your route. You can easily be in a situation where you can not get back down. Jane Dow was found 1/4 mile from the trail where she could see it but evidently she could not get back down. The condition of the remains show no obvious injury but she may have fallen a short distance. The was no spot above her that was reasonably accessible that she could have fallen from. Why a very pregnant woman in tennis shoes would even try such a stunt is baffling.
It is possible that Jane Doe went there alone. There is absolutely no way to get to the trail head except by vehicle. Supposedly no abandoned car was found at the parking but it is possible that an "abandoned" car was found many months earlier and towed away by the forest service and the Yavapai County Sheriff's Dept was unaware of it (I know of a Case in California where this happened). Why then did no one report her missing? There is the possibility that she went there to commit suicide but the same mystery exist.
There is the possibility that she was with a male companion who deliberately led her there and then left her to die. Or, there is as set of male bones nearby that still haven't been found. Either way, why no report of a missing person?
Reviewing lists of John and Jane Does, leads me to believe most are either young runaways or homeless/druggie/marginal types. Some appear to be suicides who have taken measures to disguise their identity. There are some who appear to be normal types that you would expect there to be friends, relatives, someone to be concerned and report them missing.