POLICE surgeon Robert Wells did all he could to thwart the investigation by dedicated child protection detectives - even refusing to tell officers where his flat was in Southampton.

Detective Inspector Sara Glen, who led the investigation, said: "The girls' memories had been blocked out by the drugs and this did affect the investigation because we did not have the lines of inquiry to work on. "Dr Wells also used his knowledge as a doctor to try and cover up what he had done.

"He was unco-operative and used his expertise in forensic evidence and computers to cover up his crimes. We found no DNA evidence, which is what we expected."

After tracking down his flat in Southampton, officers found drugs, camera equipment and Wells' hand-written timetable of abusing the two sisters on February 25, 2003.

This vital evidence gave times for picking the girls up, taking them to the zoo and words such as Angel Delight, Viagra and instructions for filming the abuse.

Police also seized computers from the Southampton flat and his house in Hangleton Road, Hove, which had files containing child pornography. Ms Glen paid tribute to the girls' strength, but said the abuse by Wells had left the families "traumatised and devastated".