John Stalker: I believe she had a secret

Almost from the word go, an experienced detective would know this case was out of the norm. As soon as the first routine missing person inquiries were completed, this would have been treated as a major investigation.

After 50 days, I would go back and see if anything had been missed. The first 24 hours of an investigation like this are not normally carried out by detectives and you have to make absolutely certain no one has been cutting corners.

When you are satisfied that everything possible has been done, you sometimes have to accept there is nothing more to do except hope she turns up somewhere. Sadly, in the case of an abduction, it is often not until something happens again that you get to the bottom of it.

It is a very disappointing time as often the only thing you have to look forward to is a decaying body or another murder. After a couple of months, most leads will have been followed and you have to make judgements about winding down the investigation.

As people get older, their private lives become more complex and tangled. It can take months to unravel this and some people can compartmentalise their lives so effectively that you will never penetrate that. My feeling is that there was something in Claudia's life that very few people knew about that came back and may have resulted in her death.

John Stalker is the former deputy chief constable of Greater Manchester Police