What happened to Elisa Lam?

In 2013, Canadian college student Elisa Lam disappeared while on a solo trip through California. For weeks law enforcement was at a loss to explain the disappearance -- until a maintenance worker at the Cecil Hotel discovered her body in a water tank. Ordinarily this would be the end of the tragedy... but in this case, it was the beginning of a mystery that remains unsolved almost 5 years later. So what really happened to Elisa Lam?