Natalie Wood Case -- Boat Captain Suggests Cops Could Be Withholding Info

Cops might not have been 100% honest when they said they turned up goose eggs in the Natalie Wood homicide investigation -- this according to a rep for the boat captain.

As we previously reported, the L.A. County Sheriff's Department spokesman said investigators have found nothing to lead them to believe Natalie's mysterious death in 1981 was anything but an accident.

But a rep for Capt. Dennis Davern -- named Rick Kramer -- isn't convinced ... telling us, "We don't know that there's nothing new that's been found. That would be assuming that detectives in any situation report to the public on everything they uncover."

The rep added, "What [Dennis knows] is that for the first time ever there is a serious investigation by detectives in the homicide division into Natalie Woods' death, and that is very gratifying."