WILLIAM "DUB" Lawrence is the kind of earnest, All-American guy a cop would be happy to call a friend.

Served in the U.S. Marine Corps at the height of the Vietnam War. Was elected sheriff in Davis County, Utah, in the mid-1970s, and created the area's first SWAT team.

He comes from a family of police officers, including an uncle who was shot in the head in the line of duty but miraculously survived, only to die of lead poisoning from the bullet.

And now, at age 70, Lawrence wants to draw people into a conversation about topics likely to make some in law enforcement uncomfortable: transparency surrounding police-involved shootings, the ongoing militarization of America's police departments, and whether the justice system treats citizens and cops with equal fairness.

The subjects are deftly explored in "Peace Officer," a powerful documentary starring Lawrence that opens today at the Landmark Ritz at the Bourse in Old City.

The Daily News on Wednesday hosted a screening of the film for members of the local law-enforcement community and activists who have led protests over these very issues.

The gathering, which included SEPTA Transit Police Chief Tom Nestel and Asa Khalif, the head of the Pennsylvania chapter of Black Lives Matter, had a thoughtful and at times moving discussion about the film, which we'll get to in a moment. But first, some background.

Lawrence was shadowed by directors Scott Christopherson and Brad Barber as he investigated the 2008 death of his son-in-law Brian Wood, who was fatally shot by Utah police after a 12-hour standoff sparked by a domestic dispute.

There was an extra kick in the gut: The officers belonged to the SWAT unit that Lawrence founded.

Wood, a local firefighter, barricaded himself inside his pickup truck and held a gun to head. As the hours wore on, police negotiation attempts - which bizarrely included warning Wood about how much time he could spend behind bars - stalled.

As the film shows, SWAT cops at the scene ultimately unleashed 111 rounds of various types of ammunition at Wood, including tear gas and numerous stun grenades that struck him on the head and body. He collapsed, dropping his gun, and was shot in the head by a police officer with a rifle 38 feet away.

Police officials at first told the media that Wood had committed suicide, then claimed he'd fired at the officers. "They put out information that emotionally devastated our family," Lawrence said during a recent phone interview.

The story could've ended there. But Lawrence, it turns out, is an expert at re-creating crime scenes. He became obsessed with studying the case, devoting a corner of an airplane hangar to evidence he assembled: video footage, shell casings left at the scene and investigative records.

The reconstructed evidence showed that police had flat-out lied about the circumstances of his son-in-law's murder.

The film seamlessly moves onto other controversial fatal Utah police-involved shootings that Lawrence has since investigated. Without fail, he uncovered overlooked evidence that raised troubling questions about the official police accounts.

One case - the fatal 2012 shooting of an unarmed woman, Danielle Willard, 21 - ultimately ended with the arrest of one of the officers who shot her.

The film is careful to show the danger that police officers often face, too. Lawrence probed a chaotic 2012 shootout that ensued when Utah police stormed into the house of Matthew David Stewart, who was growing marijuana in his basement.

Stewart shot and killed Officer Jared Francom and wounded several other cops. Stewart later committed suicide in prison. Lawrence, meanwhile, found evidence showing that at least one officer was wounded by friendly fire, a fact that police officials seemed reluctant to acknowledge.

"I have the utmost respect for law enforcement," said Lawrence, whose voice never wavers from a warm, even tone.

"It's a profession I've always admired and basically worshipped, because it's about the opportunity to serve and help, and because of my upbringing.

"This film . . . is not anti-police. It's designed to create dialogue, and changes for the better."

When the 109-minute film reached its end, the air seemed to rush out of the conference room where the Daily News screened the documentary. The movie is rooted in heartache, and the camera lingers on all of its forms, from crime-scene photos of Officer Francom's blood-soaked clothes to the grief-stricken gaze of Lawrence's daughter - Wood's widow - Elizabeth.

"I viewed the film not as an activist, but as a family member who lost a loved one due to police violence," said Khalif, struggling to fight back tears. His cousin Brandon Tate-Brown was fatally shot by Philadelphia police during a controversial encounter that echoes some of the film's cases.

"My heart goes out to each and every one of those family members, because I know how it feels to feel helpless when you have family members who are hurting, and you can't do anything other than scream and shout and say this is wrong."

Khalif thanked Nestel for participating in the screening and discussion, noting that the Philadelphia Police Department had declined an invitation.

"I take great pride in being a police officer. It's been my family business for generations, and I don't like it when people look at me and think of me as the enemy," Nestel said.

"I think there are a lot of people like me that want to fix things."

The conversation turned to whether procedures followed by police officers can sometimes escalate tense situations. Both Nestel and Christopher Norris, a local journalist and activist, noted that cops have to enforce policies set by lawmakers.

Utah, incidentally, has legislation that tracks the state's use of SWAT teams.

"Activists should be protesting at City Hall, not necessarily just the Roundhouse," Norris said, using the popular name for the Police Administration Building. "Some criticism against police officers are warranted, but the politicians go unscrutinized."

Local author Vincent Heck raised the issue of the rift that exists between police officers and many minority communities, a theme that largely didn't figure into "Peace Officer" because all the shooting victims featured in the film were white.

"A lot of communities aren't willing to give the police the benefit of the doubt," Heck said, "especially families that have experienced some form of police brutality."

Greater transparency could be key to rebuilding the public's trust in law enforcement, especially over controversial incidents, some say.

Kelvyn Anderson, executive director of the Police Advisory Commission, said the citizens' watchdog group still faces difficulty in obtaining records of police shootings, even though it is entitled to them.

Las Vegas, by contrast, publicly presents evidence collected after local investigations into police shootings have concluded, he said.

"Police have a different mindset. We're not always great at sharing information," he said. "But we can fix that."

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