Crime Scene Investigator Explains How Police May Crack Madeleine McCann Case

The former cold case detective suggested four detection methods which can be used to find hairs and clothing fibres at a crime scene, including different coloured lights and alternative light sources; sticky pads, which Chancellor described as 'the best collection device for hair and fibre' on a surface level; or heavy tape to pull fibres from deeper crevices and material.

He explained: "Because it was 15 years ago other methods such as visual, lighting and tapes wouldn’t have worked... For the length of time that van had been there, I would start with a visual look and then go straight to the vacuum."

Chancellor suggested the vacuum would lift possible evidence from the surface of the vehicle as well as 'stuff deposited years ago'.

One kind of material that may be easier to detect than others could be McCann's pyjamas, Chancellor said, as 'softer materials' offer a 'better chance of finding fibres'.

He went on to stress the importance of 'forensics and evidence' in cases where there is little else to go off, pointing out McCann's disappearance is 'unlike some scenes where there is overwhelming evidence at the scene like weapons, biological fluids or blood'.

Chancellor praised the work of the investigators over the last 15 years and commended the fact that 'no one has thrown their hands up and said, ‘This case can’t be solved".

“They have gone through the process up to the point of finding the vehicle, the site, and gone looking for something. That’s one of the biggest things I teach - you are never going to find something if you don’t look. I’m very impressed that they have taken the time, gone out there and said ‘We’re not done'," Chancellor added.