how is that possible???

[kat1214young]

uhh when he jumped on his back, after hitting the knife, he probably rolled to his front
ending up face down 

[Rellik]

nah, he'll be concious for a few more seconds b4 the pain is too much for him to bear.

though the first picture looked like only a small part of the knife went in him and yet a sea of blood gushed out O.o

[Chekhov MacGuffin]

lol,

but seriously is that possible? won't it be an immediate  death?

IANAC (I am not a coroner), but even though the forensics guys said instant death in chapter 7 page 8, the knife's position makes it hard for me to believe he injured something vital enough to cause death in a few seconds. Hemorrhaging is too slow (more than a few seconds), the knife's position looks a bit too low for the heart, and even if he punctured a lung he would still have to suffocate first. If he stayed conscious for a few seconds, he may have had time to turn over. Also, the soon-to-be-dead body was supported by a knife that didn't do all the way through it on a block of ice. That sounds a little unstable so it would not surprise me if the body tipped onto its side at least. (Enough morbid speculation for me.)

Totally off topic, but I think Inspector Megure looks hilarious when he is looking under the couch on page 16 of chapter 7.

[11tanm]

I think we all need to remember that these came out in the 1990s and probably were not drawn as well as they are today - even so, the plot is very good and out of the 3 series that Aoyama Gosho produced, this happened to be the most successful. I think debating about something like this is probably really pointless, but use your imagination a bit. He wouldn't be lying on his back, most likely, unless he landed completely vertically on the knife - once the ice melts, the body would probably flip over somehow or roll to the stomach. Either way, it could have been moved by the examiners when they inspected him. (I'm not a medical expert or expert on anything about this - only my imagination of what could've happened).

[HiddenDetective]

Well, for most cases with guns, knives, or other small but fast or sharp objects, unless the head is blown or cut off or stabbed hard, the victim will not die instantly. This is why Gin asked Kir to deliver a final blow on Akai's head to ensure his death (although judging by current situations, he apparently escaped death somehow, not that we never believed in him; besides, Gosho will probably not kill a fixed character).