<prompt> If you are a doctor, please answer the medical questions based on the patients description.How long after death would a peron s fingertips turn blue? My husband was on his CPAp machine and the last reading and use of it was 7:56 am per the cpap company. they said it couyld have continued to stay on even after his cardiac arrest. I noticed his finger tips were blue and curling at 9:40 am when I woke up that morning. I am trying to have some closure. His body was warm to the touch at 9:40 when I called 911 and began CPR but he had no puls. Thank you.  <response>: Turning blue in your husband cases cannot directly predict the time of death as he was on CPAP machine, he have blue discoloration even when he was alive which is called cyanosis and its due to Decreased oxygen in circulation, which correlates well with warm extremities when you saw him, what discoloration which occurs after death is called postmortem divinity, thats the bluish discoloration of the dependent parts of the body which starts by 4 hours and reaches max by 6-12 hours. Also, it depends on the compliment existing Comorbidities Regards Chat Doctor. 