I don't know. I doubt there would be any gross indicators (like petechiae incident to strangulation), but maybe there would be some subtle blood chemistry indic

I don't know. I doubt there would be any gross indicators (like petechiae incident to strangulation), but maybe there would be some subtle blood chemistry indicator. Nitrogen asphyxiation is an occasional industrial cause of death. I haven't looked in to the post-mortem data.