Tear Gas Booby Traps Have Been Around For A Long Time.......They used to be quite common accessories in safes and vault doors. A glass vial of the stuff was mounted behind the lock to defeat attempts to breech the safe by drilling the lock.
Apparently, this guy's tear gas booby traps involved hand grenades and trip wires. Contrary to popular belief, the majority of cops are NOT military veterans, and would not necessarily recognize the differance between a Frag and a smoke or gas greande, let alone what a blue tip on ordnance means. IOW, the first cop in the door saw a grenade witha trip wire and fell over herself going back out. Understandably.