I find it odd that people are recommending the book written by Goncalo Amaral, who was taken off the McCann case and convicted of perjury and falsifying documents in another case of a missing child, Joana Cipriano. This 8 year old went missing in 2004 within 7 miles of Praia de Luz, and again her body was never found. Amaral was found guilty of covering up for other police officers, accused of torturing and beating Joana's mother into a confession of murder, which she retracted the next day.
The Ben Needham case was never closed, KatyK. Excavations were carried out in Kos just last year after a man (now dead) admitted that he had killed Ben by accident and hidden his body. I'm not sure this was proved conclusively to be the case, but forensic tests were carried out on some items found that were thought to have been Ben's.