Snipped by me
(Lab tech so I’m not trained in this area, but the links give good information.)
She may have had bruising, or like you suggested tape, on and around her nose and mouth, but the signs of suffocation are likely clear.
Asphyxiation (Signs Of) | Encyclopedia.com
My guess is her cuts and bruises and their healing stages may have indicated how long she lived after the attack.
https://www.tandfonline.com/doi/full/10.1080/20961790.2018.1445441
Livor Mortis also may have helped determine time of death and that her body had been moved, and the approximate time it was left in the bunker.
****(Caution: graphic photo and information at link)****
Livor mortis - Wikipedia
***caution: very graphic link, autopsy photos*****
Untitled Document
Forensic entomology might also be a tool they’re using
Entomology | Resources | INVESTIGATING FORENSICS