Natalie Wood Investigation Captain's Polygraph Test May be Worthless

11/23/2011 12:20 PM PST

Natalie Wood Investigation -- Expert Says Captain's Polygraph May be Worthless

Captain Dennis Davern
passed a lie detector test on the details he remembers about Natalie Wood's death -- only problem is ... Davern was wasted the night she died ... so the results may be worthless.

Davern reportedly took the polygraph exam back in 2008 to prove he was telling the truth about his recollections the night Wood died -- specifically, that Robert Wagner allegedly told him not to call the Coast Guard and to cover up what really happened on the boat.

Famed polygraph expert Dr. Edward Gelb tells TMZ ... Davern's "passing" only means he is being truthful about what he remembers -- "If you believed something occurred, you would run truthful. It doesn't mean it happened ... it means the subject believes it happened."

What Davern believes and what really happened may be 2 different stories ... because he admitted (below) he was drinking heavily -- scotch and wine -- the night Natalie drowned. 

By the way, even if someone is charged with Natalie's death ... the polygraph results would not be admissible in the trial, although it's highly unlikely this case would ever end up in court.