By Mike Collett-White

VENICE (Reuters) - The scars from the Iraq war do not heal when U.S. soldiers return home, says a powerful new film starring Tommy Lee Jones that keeps the conflict at the heart of the Venice film festival this year.

After Brian De Palma's "Redacted" stunned audiences with its reconstruction of horrific events in Iraq, Paul Haggis' "In the Valley of Elah" brings a more nuanced, yet moving account of the brutality some soldiers bring back to the United States.

Jones has the critics searching for the superlatives as a man whose son is murdered after returning from Iraq, and as he pieces together what happened, the Vietnam war veteran begins to question his faith in his country and its policies.

One of the defining images of the film is the American flag flying upside down, a sign of a nation in distress.

Haggis said he had tried not to allow his personal opinion about the war in Iraq to influence "Elah" too heavily.

"We set about to make a political film certainly, but not a partisan film," he told a news conference in Venice, where the film has its world premiere on Saturday.

He said that although support for the Iraq war had waned in the United States, he began putting "Elah" together when the invasion was still popular.

"When we started on this project, our president had an 80 percent approval rating, everyone was driving around with flags on their cars and our president was telling us that it was unpatriotic to even question what was happening in Iraq.

"At that time all these films were very difficult to get financed, very difficult to make."

Clint Eastwood was among those who helped get the project off the ground, Haggis said in his production notes.

TRUE STORY

The film is inspired by the true story of a soldier whose father investigates his mysterious death near his army base in the United States in 2003. He learns his son was stabbed to death by comrades, two of whom were convicted of the murder.

Jones plays the taciturn Hank Deerfield, who downloads images from his dead son's mobile phone that offer grainy glimpses of what he went through in Iraq, and reveal that Mike was not the model soldier his father believed him to be.

Jones, 60, was not in Venice because he was undergoing eye surgery, according to Haggis.

Charlize Theron and Susan Sarandon play a local detective and Mike's mother respectively.

Theron said U.S. troops in Iraq were doing a "serious and important" job, but added: "I'd like to see them come home, to be looked after, be nurtured, and nothing would give me more joy than to see them here back in America."

"Elah" bears comparison to movies about the fallout of Vietnam on Americans -- "Coming Home" and "The Deer Hunter" -- both made after that conflict had ended.

In the case of Iraq and Afghanistan, at least six films on the topic are due out soon as the operations continue.

Haggis, whose 2005 film "Crash" was an Oscar for best picture, said this was partly because journalists were failing.

"During the Vietnam war, we had terrific journalists doing their job, reporting on things that we didn't want to hear ... Now we don't have that. I think that when that doesn't happen, then it's the responsibility of the artist to ask those difficult questions."