Gonçalo Amaral, who was chief of the criminal investigation police unit for Portugal's Algarve region at the time of McCann's disappearance, said his book will offer new information about the ongoing search for the missing child, The Observer reported Sunday.

Amaral will officially release the book in Lisbon, Portugal Thursday, just as prosecutors are expected to announce the case will be shelved due to lack of evidence.

McCann disappeared before her fourth birthday from her family's residence at the Portuguese resort of Praia da Luz on May 3, 2007, and Amaral is said to believe she died following her apparent abduction.

The Observer said Amaral's book is expected to include allegations of improper police work by British investigators who he suspected of mainly following leads supported by Madeleine's parents, Kate and Gerry McCann.