After reading your explanation I have to agree with you. The face-down theory made sense.
About the "suffocating" soldier. In 2004 I investigated a murder where the victim was shot twice with a 9x19 124 grain FMJ. First shot was through the right hand into the chest (through the nipple line between sternum and RH breast) and it exited cleanly.
The victim spun around and was shot again with 1/2" of the exit wound, so both wounds appeared like the number '8' on his body.
He ran a short distance, through an apartment complex and collapsed at the door of a fellow Norteno gang member. They dragged him inside and propped him up against the wall. Pink froth seeped from the wounds and there was a good deal of blood on his clothing and the floor.
The victim's friends tried to stop the bleeding for 10 minutes or so, not wanting to call police (which hadn't been called because shots fired calls in that neighborhood were so common) and they didn't call 911 until he passed out.
When I arrived, he was in the same posture as the suffocating soldier. He still had pupillary reactivity and a faint pulse. However, he was turning blue around the lips. By the time paramedics arrived, agonal respiration had set in. They started a vent (chest tube) and worked on him for a few minutes, but never could restore a heartbeat.
At autopsy, the bullets missed the ribs entirely and only tissue and blood vessels were involved. The coroner said the shots punctured the RH ling and damage from both the bullet and temporary cavity destroyed blood vessels and he suffocated when the chest cavity filled with blood.
It was a terribly painful expression and his eyes were wide open as if he saw something that scared him.
I don't miss those days at all...