He's a biographer who has been around a while. He has decent credentials as near as I can tell. All the stuff he put in his book came out in the months following the plane crash.
From his Wikipedia:
Edward Klein is the former foreign editor of
Newsweek and served as the editor-in-chief of
The New York Times Magazine from 1977 to 1987. He frequently contributes to
Vanity Fair and
Parade and writes a weekly celebrity gossip column in
Parade called "
Personality Parade" under the pseudonym "Walter Scott." (The Walter Scott pseudonym had originally been used by
Lloyd Shearer, who wrote the column from 1958 to 1991.
[3]) He also writes books, many of which have been on the
New York Times Bestseller list. Additionally, he was the principal for the Business Communications School at The Euclid High School Complex. He was photographed by popular
Humans of New York photographer Brandon Stanton, on June 12, 2014, which led to his personal website crashing due to a high volume of visitors.
[4] Klein is also a contributor for the
New York Post.