Where?
From one finger to another finger or on the surface of the skin. Where would .2 amps driven by a potential of 5 VDC kill? Read up on how the human body reacts to DC currents.
Dear one, I am well aware of all of this stuff. A .20 amp current through the heart will kill it. Water on the skin significantly reduces skin resistance. From the skin on her hand into her blood stream or nervous system should be more that 25 ohms, but was it? Once in the blood stream, the electrical resistance would be quite low due to the electrical nature of the nervous system and the electrolites in the blood. The exit point from her body was basically the entire surface area in the water. That would be a parallel resistance, quite low for that large surface. That is a clear path through the heart.
Now, it the phone was plugged into its charger, water could have run down her arm, down the cord, and into the charger. That could have made a connection to the 120V AC of the electrical outlet. Given the electrical path previously discussed, we would find that something well over 25 ohms would pass .2 amps, like 600 ohms by computation.
Here is another scenario that wasn't discussed. Suppose she actually got zapped by the RF from the cell phone. If the tower was far away the phone could be using up to 5 watts of RF power. Given a nice wet path through her head into the drain, I give that a good possibility.
All of my posts taken together convey a lot more information than yours.