Enter Pancuronium Bromide (Pavulon). It’s a powerful muscle relaxant used for anesthesia. If you inject it into a patient who isn’t on a ventilator, their lungs stop. They don’t struggle; they just... fade.
When a patient dies in a hospital, you look for a cause. If you can’t find one, you look at the chart. If the charts are clean, you look at the toxicology. This was where the "Angel" made his fatal mistake.