Winterbottom told The Independent: "Whenever you make a film based on a true story, and I have made a lot of those, you have to deal with it as honestly, accurately and sensitively as you can."
Film magazine Empire described the filmmaker as having "a strong track record in handling true-life stories with care and diligence". Those include Mighty Heart, about the search for the Wall Street Journal reporter Daniel Pearl in 2002, and Welcome to Sarajevo, about ITN reporter Michael Henderson in the besieged capital of Bosnia and Herzegovina.
"Our film is trying to get back to the important point that a family has lost their daughter and that is the heart of the story," he continued. "The Kercher family behaved with an incredible amount of dignity through a very difficult situation. We don't want to do anything that would be upsetting to the people close to the case.
The Face of an Angel, which stars Kate Beckinsale, Daniel Bruhl and the model Cara Delevingne, looks to use the case to explore the sensationalising of murder trials and society's fascination with violence. "The heart of the story can be lost among the sensational elements, with the soap opera instead going on for years," he said.
"This case is an extreme example of the phenomenon of TV news and newspapers reporting violent crime," Winterbottom said. "There was a huge amount of press attention. Then there were the many books and TV documentaries as well as a TV film."
He said: "Talking to Barbie and others, they were aware they focused on sensational elements that sell. What goes missing is the person who's the victim."
Winterbottom met the Angel Face author two and a half years ago. "I hadn't followed the case that closely and I read her book by chance," the director said. "I thought she was an interesting character and could be a starting point for the way the media treat cases like this." He added that the foreign correspondents in Italy proved to be a parallel "of the story of students from different cultures going to Italy in the first place. It was the starting point".
Knox and Sollecito were found guilty of the murder of Kercher in 2009, but the verdict was overturned in 2011. The acquittal was overturned two years later, and last week the retrial of the murder charge affirmed the verdict of guilty.