[mom4kittys]

I thought of that too, but maybe if someone is administering the drugs other than ANS, it could be considered a crime, intentionally or not. It would also rule out suicide.

[stlnative]

I'd say he found an recent injection site on her body that she could have done herself. The outer skin would be fairly clean around that injection site if someone used a alcohol swab. Perper wants to know she was in the habit of using alcohol swabs before she injected herself.

Anyone in the medical field or anyone who injects themselves often knows that you should use a alcohol swab.

My guess is this injection site was not cleaned with a alcohol swab and Perper knows this. He also knows what was injected at the injection site as tissue in that area would have more drugs in it if the injection was recent.

Still it does not show if she injected it herself to commit suicide or if someone else did it to kill her. Plus we don't know if she used sterile methods in the past when injecting herself. Perper is using the process of elimination by finding out her habits.