A 'German paedophile' is said to have written about Madeleine McCann's disappearance online, claims a detective investigating her case.
The former detective says investigators previously probed a child sex offender's chatroom activities before police announced a new prime suspect yesterday.
In a bombshell revelation, officers announced they have identified a German prisoner as a suspect, as reported by The Mirror.
The 43-year-old is known to have been in and around Praia da Luz on the Algarve coast at the time she vanished on May 3, 2007.
It comes as one of the most significant breakthroughs in the search for Maddie in recent years.
The suspect has now been unmasked as Christian Brueckner.
German state prosecutor Christian Hoppe confirmed the suspect is a paedophile who has been convicted of sexual abuse against children as well as other sex crimes.
Mr Hoppe, from Germany's Federal Criminal Police Office (BKA), told the country's ZDF television channel the 43-year-old is serving a prison sentence for a sex crime and has two previous convictions for "sexual contact with girls".
The suspect is reported to have been living in a campervan in Praia de Luz around the time Maddie vanished.
The Times reports a chatroom clue allegedly concerning a German man had previously emerged in the missing persons inquiry.
Goncalo Amaral, the head of the original Portuguese police investigation into the toddler's disappearance, said last year that detectives had looked into an Internet chatroom exchange.
According to the newspaper, Mr Amaral claimed that a German paedophile suspect had been ruled out of the inquiry in 2008.
The former detective described the man as later having been jailed in Germany for child sexual offences.
"Many years later, it appears that in an Internet chatroom there is a conversation between that person and another person where they talk about Madeleine," he said.
The prime suspect police revealed they are looking into last night is described as white with short blond hair, possibly fair, and about 6ft tall with a slim build at the time Maddie vanished on May 3, 2007.
In 2013, Scotland Yard had said that a blond man had been sighted near the apartment where Maddie was taken from, where she was staying with parents Kate and Gerry McCann.
Yesterday evening detectives said the e-fit of the man that was released at the time had 'not been ruled out'.
