Whether it's possible or not, being a doctor, you take an oath. To care for your patient, not to kill them. You take an oath to do things that are proper in the medical world. Not to administer something outside of a hospital setting that's not even your area.
“I have zero hand-eye coordination - zero - so I've never been good at softball, basketball, golf, things like that, but I'm really strong and I have really good endurance so I can go forever - I'm a tough girl.”
“Arsenic sticks around and today it's easily found after death if somebody thinks of looking for it, because the problem with arsenic, it isn't looked for in the common tests for drugs.”