Does it say any place that her purse was found on dry land and not fished from the canal by our credit card thieves?
Maybe when she fell, the purse went with her, both floating in the canal, only now they are separated and the purse got hung up on something or because of size and weight, each floated at a different rate.
The boyfriend had said he heard her walking on what sounded like gravel. She was inebriated, and unsteady on her feet, no doubt. With loose gravel, her attention being on her phone call, she very well could have just lost her footing and fell in, purse and all.
I believe it was an accident, a horrible chain of events that ended in a tragic outcome. I think the credit card theft was a crime of opportunity. IMHO