A convicted serial killer has emerged as a key suspect in the search of missing Madeleine McCann, according to reports.

48-year-old Martin Ney, who was sentenced to life imprisonment in 2012 for multiple child murders and abuses in Germany, is reportedly being investigated by officers from Portugal’s Policia Judiciaria as a “figure of interest”, AAP reported.

“Detectives are preparing the end of the investigation, with a German paedophile who is in prison right now,” said former Portuguese police chief Goncalo Amaral, who first led the search for the young girl.

Ney is believed to have been in Portugal when McCann vanished in 2007. It is claimed that he was working for an evangelical church on a project to help the homeless then.

Police believe that Ney resembles a photofit of a man who was seen acting suspiciously in Praia da Luz before the then three-year-old McCann disappeared from her family’s holiday apartment in May 2007.

Ney has previously been interviewed by detectives investigating McCann’s disappearance but has denied any involvement.

Last Friday, May 2 marked the 12th anniversary of McCann’s disappearance. McCann’s parents, Kate and Gerry McCann, said in a statement released on the day: “Thank you to everyone who continues to support us and for your ongoing hope and belief.

“The months and years roll by too quickly, Madeleine will be 16 this month. It’s impossible to put into words just how that makes us feel. There is comfort and reassurance though in knowing that the investigation continues, and many people around the world remain vigilant.”