He assumed it was tyre marks and that it could lead him to the car. "I thought it was [going to be] the easiest hit and run I had ever worked on," he says.

But he knew something was wrong when he noticed that the trail kept going and going - for three miles (4.8 km). "The more I went the more my heart was beating." Eventually he checked the dark trail. "It was a brown dark substance, but it wasn't tyre tracks," he says.

It was in fact a mix of blood, flesh and bone of James Byrd Jr., a local black man. Byrd had been picked up by three white men during the night, beaten, chained to the back of their car and dragged for three miles. A pathologist believes Byrd was conscious for part of the time he was dragged. His arms were worn down to bony stumps in attempts to lift himself. His head was decapitated on a drain culvert, his torso found further down the road.

With that kind of subject, Two Towns of Jasper, which screens in the Wellington Film Festival on Monday and Tuesday, sounds riveting enough. But the American documentary, which premiered at the prestigious Sundance Film Festival earlier this year, is also ground-breaking. In a first for any stud on US race relations, two film crews went to Jasper to record the aftermath of Byrd's murder. One crew - producer and director Marco Williams and cameraman Jonathan Weaver was black, the second - producer and director Whitney Dow and cameraman Steven Miller - white.

The black film crew spent a year filming and interviewing blacks, while the white film crew did the same with whites.

Williams and Dow, friends for 20 years, will be in Wellington for the screenings. Williams says the seed for the idea of making the documentary with separate black and white crews came from the pair's first reaction to news about Byrd's horrific murder. "The more Whitney and I talked about trying to make a movie about the murder and the implications and ramifications about it being racially motivated, we occasionally turned to the conversation he and I had when he first called me up and asked 'What do you think about this murder in Texas?' I expressed the same level of shock and outrage that he had felt. But I also introduced another opinion - that I was not surprised. I expressed that blacks had been brutally murdered for quite some time in the US.

"We constantly went back to that because that's where we diverged, at least momentarily. Even though we had similar backgrounds - north-east (US) born and raised, ivy league colleges - there were occasionally differences and the differences always came to our racial identity."

Williams says with that in mind, eventually they decided the best way to make their film was with segregated crews. The crime had divided the town and it was likely the only way people would feel comfortable and open up to being interviewed was to people of the same race.

"People wanted to speak candidly about how they felt. It's a much greater challenge to speak across a chasm of difference when that's the very thing that was being exposed."

Williams says if race wasn't so much at the heart of the film, a mixed crew may have worked. Could he have filmed the whites and Dow the blacks? "Certainly. But would there have been the level of candour? Not likely. The film would have needed to have taken on a more confrontational methodology in order to get at something expressed in the film."

The candour can be shocking. In one scene, about a year after the murder, a group of mainly elderly white businessmen and women talk about the impending trial of one of the killers. The harmless-looking bunch don't believe the white men are innocent, but spend most of their time discussing that Byrd was no angel and a bad role model for children. The implication is that he was somehow to blame for his murder.

Williams had never heard of Jasper, a small town of 7200 people in East Texas, before the killing. Prior to the main filming, he and Dow made several trips. Williams went there alone. "I arrived in Houston at 5pm, it's just about dark and I get in a car and I have to drive about two hours north east. At a certain point I'm on a two-lane road that's completely dark and I'm reliving the opening sequence to the American film Mississippi Burning. I kept expecting, with every headlight that came on behind me, [that] I was going to be rammed off the road."

Williams says while in Jasper most people, including whites, were generally friendly or polite - in the tradition of "southern hospitality." Only once, when ha and Weaver were buying takeaways, did they felt they were being treated badly because they were black. White people were served before them, even though they were there first. He also believes whites were, to a degree, more guarded about expressing their views because the town was under the media spotlight.

But what surprised Williams was that Jasper didn't fit his idea of a racially divided town. The mayor was black and there were some prominent black businesspeople. Furthermore, instead of being a tiny minority, blacks made up 45 percent of the population. Williams, being a northern black and used to speaking his mind, was also caught off guard by Jasper's blacks holding back much o their anger over the murder. "It took me a little bit of time to appreciate why that was. Blacks were afraid for their jobs and their lives. There are two or three times in the film where you hear somebody talk about 'This is not the first time this has happened' or 'We have skeletons in the closet.' They really were the powerless."

Williams and Dow wrote up a "manifesto" to make the film. The two crews stayed in separate accommodation and didn't communicate, except for brief meetings once a week. The crews also didn't tell interview subjects that they were in fact two crews making the same film, unless asked. With it being such a small town, you'd think people would have worked it out after only a couple of weeks. But Williams says few people realised simply because Jasper was so strongly segregated. However about half-way through filming he started telling people that there was another film crew. "All to a person would say 'That makes perfect sense' because for them they couldn't imagine having a candid conversation about race across race."

The two crews were in Jasper for all of 1999, following the three trials of Byrd's murders - John William King, Lawrence Russell Brewer and Shawn Allen Berry. Each crew followed 15 people, including members of Byrd's and his killer's families.

Some scenes are hard to forget. District attorney Guy James Gray holds up large photographs of tattoos on the three killers' bodies - one has the silhouette of a black lynching; members of the Black Panther Party carrying guns arrive in town; Trent Smith - mobile phone salesman and member of white supremacist group Aryan Circle shows off his white power tattoos.

The 90 minute film was whittled down from 240 hours of footage. Editing also involved a novel approach. Dow edited a rough cut with a black film editor and Williams with a white film editor. The result was two separate documentaries. Next a third editor was brought in to integrate the two films into the final cut.

"Both of us feel that there are essential critical stories and sentiments that are languishing on the editing room floor that never made it into the film simply because we were committed to making one."

Williams and Dow have yet to screen the documentary publicly in Jasper. In June the two did screen it to the people in the film. "Categorically, everyone who saw it really liked the film and had no problem with what was expressed, captured or ultimately presented.

"It is our hope that we will do a screening in the town and use it as a platform for a broader discussion about race."