RSBM
Good question. I suspect by now, they've all been disposed of.
There are only 2 scenarios that make sense to me based on what we know (maybe others have thought of more?)
1. She was undressed after death to hide any evidence of the person/location (hair, fibers, dirt, etc. - people wrongly assume they know what they're doing since they've all seen CSI) she was at, at the time of death - then dumped on the side of the road. Clothes and personal affects dumped elsewhere, afterward.
2. She was undressed at the time of death, and whoever she was with panicked and dumped her on the side of the road, then went back and gathered her things and disposed of them elsewhere.
Considering "awareness space" (the geo location most familiar to the perp, roads, landmarks, routes to and from work, etc.) I suspect it's likely that not only her body, but all her clothes, purse, phone, etc., were all dumped in a fairly close location to where the perp lives/works.
Of course I could be way off, but this does seem to play out this way in many, many cases.
jmo