Not if she was on her back in the fire. Keep in mind that he didn't even manage to burn all of her hair (which is really unusual, it's easy to do).
Also, those ties aren't going to completely disappear in heat. If you've ever looked in your own firepit if you tossed beverage rings (those plastic six-pack thingies) or zip ties in there - they will still be there, only a bit deformed, afterwards. Rope is hard to burn through (string, yes, but actual rope - it's going to take a while, not enough oxygen getting to the core of the rope for it to remain on fire). Since the rope was wrapped around something, the parts where it is not so exposed to oxygen aren't going to burn well. That being said, there are ways of making rope very flammable (but that would have to be pre-prepared).
People who use accelerants (gasoline) to start fires get a really big fire going, but as soon as the accelerant is exhausted, much of what they tried to burn is still there, just charred on the surface. This type of fire is good at deforming things (like suitcases) but will not burn up the evidence that the suitcase (or the zip tie) was there. Zip ties are actually pretty sturdy. Even plastic bottles don't completely disappear. Repeated applications of gasoline will reduce the items each time it is used...