How did Stalin's second wife die?

Stalin's second wife, Natasha Alliluyeva, was found dead in her bedroom. Natasha was dead from a pistol shot and a suicide note was on her nightstand. There was evidence that she might have been murdered. She was shot in the left temple, implying that she used her left hand, but Natasha was right-handed. In addition the doctor who did the autopsy reported that there were no powder marks on her skin and the gunshot took place from at least three feet away. That doctor was executed.