(CNN) Actor Robert Wagner remains a "person of interest" in the death of Natalie Wood but has thus far declined to speak with investigators since they reopened the case in 2011, according to authorities.

Lt. John Corina, of the Los Angeles County Sheriff's Department's homicide bureau, said in a press conference Monday that the details Wagner has offered up on the fateful night "really don't add up to what we've found."

"He's a person of interest because he's the last person with her before she went in the water," said Corina. "This is a suspicious death investigation. We want to know what happened from the time of the argument to when she got into the water."

CNN's calls to a representative for Wagner were not immediately returned.

Corina added that Wagner is not obligated by law to speak with investigators, but said "we're closer to understanding what happened, I think."

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