[SaltyJoe]

"why the hell did they rip his friggin pants off?"

Loss of bowels/bladder control. Perhaps to clean him up. Fecal matter and urine don't do well with open wounds. If you ever see photos of Chinese executions, they usually tie up the pants legs with string probably to keep the dead bagged up as much as possible (with exception to the large caliber bullet effects on the head and face).

Don't mean to gross you out. Dying is often embarrassing and sometimes messy. Violent death generally is messy.

This is the effect of sin upon mankind.

[Rb ver. 2.0]

If you look at the photos this guy is pretty clean below the waist. More likely his pants were stripped to rob him and check for a money wad stuffed in his pants.