Given that Jang Mi-ran's autopsy finished in 30 minutes, it must be skeletal

In reality, if it's not something like a fracture, there probably isn't much that can be found.
According to media reports, there are no fingerprints (which is expected since it's skeletal) and identification was done via dental records.
Based on the fact that this is all there is,
even if it were a case of rape followed by strangulation as people suspect, it would be difficult to find evidence.
If it was suicide, there was definitely no rope when they left, so they will have to confirm where the rope came from.