Executive producer Roger Graef on death, data security and filming a family tragedy.

Cutting Edge: The Millionaire and Murder Mansion
Executive producer Roger Graef
The challenge Gaining access to the relatives and burnt-out site during the investigation into Christopher Foster's murder of his wife and daughter
When Christopher Foster burned down his house and killed his wife and daughter, the nation was gripped by the unfolding drama. West Mercia police embarked on the most high-profile investigation of their careers. The remaining Foster family were in shock. Kevin Sutcliffe at Channel 4 rang our colleague at Ten Alps, Fiona Stourton, about access. She rang us. At Films of Record, we try to get into places other film-makers haven't reached.

I've filmed police for 30 years and met a lot of top cops. We filmed West Mercia police chief Paul West for Police 2001. We've stayed friends since.

But with such intense scrutiny around the case, West Mercia worried about filming the ongoing investigation. While police sifted 40 tonnes of rubble, time was running out. With Foster deemed the killer, they were not looking for suspects, just victims' remains.

We had to convince them to let us in without delay. But they wanted a contest between candidates. Three weeks later, director Nick Poyntz and I travelled to police HQ itching to get started. Our track record impressed them, but it was not a done deal.

We wanted to show the complex police investigation and the human drama of Foster's family and friends. But we didn't expect the police to deliver the family. A week later, the police chose us.

We started filming on the burnt-out estate and, unusually, in the morgue. We were planning interviews when the police solicitor intervened: the Data Protection Act obliged them to get written permission to pass on interviewees' contact details. But it didn't stop us.

Nick and producer Adrian Gatton went direct to the family and friends. Most had yet to speak to the media. This was the most difficult and bewildering point in their lives. Chris' brother Andrew decided to break his silence to tell the truth about his brother. His mum Enid also agreed. So did his sister-in-law and friends, with widely differing views.

We learned things the police didn't know about the Fosters' lives. Enid, 76, could only see the good side of her favourite son Christopher.

The family's honesty and quiet emotion opened up the facts and leaves you wondering how you would cope if your child or friend did something horrible. Would you, as Enid says, forgive your children whatever they do?
Cutting Edge: The Millionaire and Murder Mansion airs on Channel 4 on 9 April at 9pm.