It is most likely that the "charger" did not electrocute the person. However, the 115 VAC 60 Hz electricity that the charger plugs into will.
I don't think that is what did it, simply because the wall wart is close to the wall with only a 5V lead into her phone. Wet all over, her body had a significantly reduced electrical resistance giving an easy path into her blood stream, which is largely salt water. I suspect water ran down her hand, down the cord, and into the connector. The 5V apparently did push up to .2 amperes into her nervous system, which is all it takes to kill someone.
Dry skin exhibits over 300,000 ohms of resistance. Wet skin, maybe a hundred.