The movie Dead of Winter is based on a true story, but which of the events were true?

i remember watching an episode of 20/20 were a guy and girl took LSD
(not sure if it was accidental or not) and ended up stranded in the
woods and there was snow and they called 911 and told them there were
people around them but that they couldn't get them to respond to them
(later police discovered some cows, and so they think this is what the
hallucinating couple mistaken for people).

so now on Netflix theres a movie called Dead of Winter about a couple
who took LSD accidentally and ended up stranded in the woods with the
snow and basically the same thing that happend with the above story
^^^. but i want to know which parts of the story really happened. for
example, did the female deputy really die? did tiffany really kill
her? what happened to her boyfriend? did tiffany really survive in
real-life?
Steven that didn't help one bit.