Well let me think about who killed henry:

there are 5 posible characters so far: Undying, The Face, Greg, GOD or lisa.

By prosses of elimination, we know that if It wasnt a suit or a humanoid, It was the SSA, because when henry says "They might be listening" he could only mean suits or SSA so lets focus on that now.

Since greg and lisa havent been to Treasure island for a single night, so they arent guilty of anything YET.

so now im going to go for a suit... We see The Face in Night 3 so he is looking for jake.

GOD or undying?

Undying could be gulity, If he kills Henry in night 3, we should see blood on him when in pirate caverns and we know he is fisical because he cant escape the cage so why can he be guilty? with the new information we know Henry whent into the cage but there isnt blood so Undying cleant it.

God could have also done it because she is a ghost in sertain part so she cant get splatterd.

In conclution Undying did it: If henry was killed in the cage. Were did the blood on the elevator come from?, its visualy fresh. So henry ran to the elevator after leting Undying out he droped some papers and his camara but didnt made it, he was Killed by Undying wich claned himself and all his room.

The game over screen shows a mickey head with yellow blood coming out, only suits bleed yellow, That means there is death inside so if someone kills jake, Jake becoes a humanoid and then someone rekilled jake to lead to the game over screen (shade Suicide mouse has blood on him, confirming that natural blood is Red)

Going on further: Wile Jake was in watch God Hurt henry because of the SSA (wile henry is humanoid meaning his blood should be Yellow) in the elevator so that explains the yellow blood, it also explains why henry is mising an arm, henry is also yellow so we couldent see if he had any blood on him. also explains why There is no yellow blood splatterd on any character.

If you find a hole on this tell me.

It could also be that henry is not dead and he was supposed to die in another night.

also if there are no holes i just solved a huge mistery to FNATI. But hey that's just a theroy, a Game theory.