What is Missing 411

Some park rangers allegedly spoke with David Paulides, former law enforcement and told him there were mysterious unexplained disappearances in national parks, and there wasn't much investigation done into them
Paulides asked the park service for records of people missing in Yosemite using a freedom of information request. They said they did not have a list. $34000 for a list of missing people from Yosemite because they'd have to pay staff to put one together. Paulides, a published author, asked for the list using his author's exemption, which waives the fee. He got a call back from a national parks service attorney who said his books weren't in enough libraries to grant the exemption. Paulides asked how much it would cost for all 383 national parks in the US. The attorney said that would cost $1.4 million. (link)
David Paulides requested the case file for Stacy Arras. His request was denied, even though they have an extensive case file, and not even the family or local congressman could get the file, despite the case not being actively investigated. (link). He also found the park service does not take the situation seriously (link)
Paulides started researching missing persons cases to put together his own list and after researching many cases, found that there were common themes and many cases had no obvious explanation and remained unsolved. From those themes he created a profile and a pinboard that plotted disappearances that match the profile, like how the police might when doing an investigation. He excluded cases that involved things like animal predation, potential drowning, and suicide risk. Though he later wrote about some similar cases that did involve drowning as well as mysterious circumstances.
He found that often people were found in locations and at elevations that were outside of what search and rescue manuals suggest.
He found that there is a criterion used by the national park service where if someone is presumed dead, they are considered dead instead of missing and are removed from missing persons lists and mostly forgotten about. This results in no awareness of the case, no accountability for the parks service, and no safety improvements for the public. (link)
He found that the park service and law enforcement sometimes treats the families of missing persons badly. Example:
Joe Kellar's family
Dennis Martin's father.
Diana Zacarias parents.
The wife and son of Dale Stehling (The Malliard Report, Aug 2016)
He wrote several books about the cases to show the issues, and made a documentary about it that is due out in 2017.
Contrary to people saying he thinks bigfoot is the cause, David says he just shares the facts and does not offer any theories about what might be the cause of the disappearances he writes about, and won't give an theories until "until we are certain that specific, consistent elements exist that point to a cause" (link). Some people say he leaves out details so he can sell books, though his research has held up fairly well to scrutiny so far, even if it's not perfect (link), and has uncovered some important issues about how missing persons and their families are handled. (link)
I am summarizing this from what David Paulides has said and what can be found by independent research. There is debate about how accurate everything is, though most criticism is not very good or definitive. It is difficult to verify some claims made by David about personal conversations he has had or proof he hasn't publicly shared, though some things can be verified independently.

Info from the Black Vault. http://www.theblackvault.com/casefiles/?s=bigfoot I will look later to try & dig for anything declassified on Bigfoot.