Maybe the drug couldn't circulate in the body and stayed near the injection site because she was dead.
Kinda like turning on the garden hose and waiting for it to FILL and get to the nozzle. Turn it off (kill the pumping action) before it gets there and no water at the nozzle. Simple hydaulics but I've forgotten the formulas. It's been 20 years.
If that is the case, those people are idiots if they gave an injection and didn't notice she was dead.