Can finger print from deceased person be used to open his iPhone

There are 3 basic ways to open an iPhone: 1)typing in the 4 number password code, 2)using your finger print. and 3) using Siri- I am not sure about Siri but it should work since you use your voice.-all you need is the recording. Areas where being able to unlock cell phones include where a person dies suddenly and the person did not leave such data in their will or in cases of terrorism where victims involved in terrorism and killed by the police, and companies like apple refuse to unlock the phone of such victims for the police , I wonder if their fingerprints could be used to open their iPhone devices if they had used this method to unlock their cell phone device. One would easily test it by going to a post mortem room and place the thumb on the home button of the iPhone - or whichever finger they used for opening their iPhone when they were alive. I don't know whether the finger print is altered shorty after death by rigour mortis changes.If it is not successful, I wonder whether fingerprints found in police files could replace the fingerprint method for opening iPhones or similar devices.In any case it would be easily tested. A note of caution to the police police: when killing your suspected terrorists try and save their upper extremities especially the fingers and/or thumbs.