She knew the drill because she killed Dean with lethal dose 2 months prior. Who knows have many more times that we do not know of.
rsbm
Yeah, my problem with that is, if she had intentionally killed before and was all murderous black widow like that, why would she need to google what to do? Seems like something a person would do in a panic. I kinda doubt an experienced killer would panic like that.
I also doubt she'd be wanting to cook heroin in a spoon in front of her big-money clients, that's a pretty skanky thing to do, not very sexy at all. So bringing a pre-prepared syringe makes sense, in her situation.
I honestly think people maybe *want* her to be another Wuornos, including the cops - but everything I'm seeing strongly suggests she was just a gormless junkie whose 'dates' and boyfriends dabbled in drugs too, no matter how much their loved ones want to believe they did not.