On the front line in the search for Maddie

It is a shame that this revealing memoir from Gonçalo Amaral, the police chief who ran the Madeleine McCann investigation until he was unceremoniously fired last year, has not been published in English. It's also a fairly safe bet that it won't be. Within minutes of its appearance in Portuguese bookshops, the McCanns' spokesman let it be known their lawyers would be giving it a thorough read, with an eye to the kind of libel action that ended up costing the Express group £500,000 earlier this year. And that was before the Portuguese authorities finally cleared the couple last month of any suspicion.

But it's not just lawyers who have been reading it. The book is, the publisher reports, swiftly heading to the top of Portugal's bestseller list (although, given the size of the country's book market, this is likely to earn Amaral more fame than cash). Surely it won't be long before enterprising translators feed the juicier bits to an online conspiracy community that, in the 15 months since the cherubic three-year-old went missing from Praia da Luz, has elevated Madeleine into something close to a new Elvis. Or in the phrase Amaral prefers to use, with no evident trace of irony, in the book's acknowledgements: 'cybernauts and bloggers who have been defending the cause of truth and justice.'

The least surprising, as well as the least convincing, section of the book is its conclusion, which basically echoes the case Amaral had failed to make before he was fired, and Madeleine's parents were cleared: that the little girl died in her family's holiday apartment, 'perhaps as a result of a tragic accident', on the night of 3 May 2007, that there followed a 'fake abduction', and that her parents 'are suspected of involvement in the hiding of the body of their daughter'. This reviewer - as well as any objective person - would surely by now have ruled out any of these possibilities. The book does nothing to change one's view that there is no plausible case against the McCanns. Helpfully for the McCanns' lawyers, particularly now that they and a third former arguido, Robert Murat, have been cleared, these assertions are all printed in bold type on the book's final page.

Much more riveting is Amaral's detailed account of the investigation he led from the night Madeleine went missing until last October when, after he allowed his anger over what he saw as British obstructionism to seep on to the front page of a Portuguese newspaper, he was dumped from the case. Nothing that Amaral says adds up to a solution to the mystery surrounding Madeleine's disappearance and there clearly isn't enough here even to build a coherent court case. Amaral is completely at odds with his own attorney general in his interpretation of events, as Clarence Mitchell, spokesman for the McCanns, has pointed out.

But Amaral's account does provide a glimpse of the sheer scale of the work he, his colleagues and visiting contingents from Britain brought to bear on the investigation: knocking on some 400 doors in and around Praia da Luz, interviewing hundreds of people, sifting through forensic evidence and posting timeline after timeline on the walls of their headquarters in the nearby city of Portimao.

Mistakes, clearly, were made, most glaringly the failure to secure, photograph and scour the McCanns' apartment and the surrounding area as a potential crime scene and avoid the possibility that potentially crucial evidence had been lost or contaminated. Yet even for those of us who happen to believe that Elvis is no more, the book offers a page-turning compendium of unexplained puzzles - as are so frequently found in wide-ranging, complex investigations.

As it happens, I was in the middle of Kate Summerscale's award-winning account of a Victorian murder case, The Suspicions of Mr Whicher, when the review copy of A Verdade da Mentira arrived from Lisbon. Putting Summerscale down in favour of Amaral was a bit like switching from In Cold Blood to, well, Cybernauts Seeking Truth and Justice.

But Amaral does write, if not poetically, then fluently and, at times, grippingly. Moreover, his account contains inescapable echoes of Summerscale's eloquent insights into our abiding fascination with detectives and detection, particularly when a mystery remains unsolved. And doubly so when the mystery invites vicarious intrusion into the suddenly tragic private life of an ordinary, middle-class family.