Natalie Wood Death Investigation -- Exercise in Futility

Sources in the L.A. County District Attorney's Office are scratching their heads over the Natalie Wood death investigation, because they say there's no way the D.A. is going to prosecute Robert Wagner or anyone else.

Although the L.A. County Sheriff's Dept. says Robert Wagner is not a suspect, it's pretty clear -- as the last person to see Natalie Wood alive -- he's the target of the probe.

Under California law, even if Wagner accidentally pushed Natalie into the dark water ... the most he could be charged with is involuntary manslaughter. But here's the problem -- there's a statute of limitations of 3 years for that crime, so prosecutors would have had to file charges 27 years ago. Ditto voluntary manslaughter, which has a statute of limitations of 3 years.

The only crime for which anyone could be prosecuted is first degree murder, because there's no statute of limitations. Remember, there are no possible witnesses other than Robert Wagner. Short of a bizarre confession, D.A. sources say there's no chance of a prosecution. BTW, there's a 6-year statute of limitations on second degree murder.

As for why the Sheriff is investigating the death ... one D.A. source said, "It's an exercise in futility. I just don't get it."