Cops uncover sensational new forensic evidence in secret CSI investigation of the NATALIE WOOD death ship,  The National ENQUIRER has learned.

In a startling and dramatic new development, forensic detectives probing the mysterious drowning secretly flew “Splendour” boat captain Dennis Davern to Hawaii so he could walk them through – step-by-step – Natalie’s terrifying final moments before she plunged to a watery demise.

The ENQUIRER has learned cops conducted a series of “noise tests” over four days in a bid to substantiate Dennis’ explosive eyewitness account of what he said REALLY took place on the mysterious night of Nov. 28, 1981, while boating off the Southern California coast.

Dennis – who passed a polygraph test administered to him by police – specifically has implicated Wagner in Natalie’s cold case death, and his information helped authorities reopen their files in 2011.

While Wagner has strongly denied fighting with his wife, Dennis has provided explosive testimony that the troubled couple had a vicious argument that he heard and partially saw before Natalie, 43, disappeared off the boat.

While Robert Wagner, 85, has not been named “a suspect” in Natalie’s death, Lt. John Corina  told The ENQUIRER that he – along with Dennis and Walken – is now classified as “a person of interest” in the investigation.

He said that determination was made after the L.A. Coroner’s Office changed the cause of Natalie’s death from “accidental drowning” to “drowning and other undermined factors.”

For the full story with all the details it’s only in the new National ENQUIRER – on sale now!