The search for missing Madeleine McCann continues in Portugal, as investigation reaches new developments with four suspects or "arguidos" targeted for questioning in regards to the case.

Upon searching for evidence in three areas of Praia de Luz, British police have come up empty handed. Now four "persons of interest" are set to be questioned due to their links to other crimes against the Portuguese judicial system.

One of the four "arguidos" to be interviewed is Sergey Malinka who was questioned initially as a witness back in 2007. Malinka is a Russian-born computer expert, with a Portuguese national background; he will likely be questioned on Wednesday.

Local Briton Robert Murat, who was interviewed by the BBC, strongly discouraged the questioning of Malinka, "It's absolutely ridiculous. It makes no sense. They've talked to him before, in 2007, so why are they talking to him again? He's a good professional and a hard worker. I don't know Sergey that well, but he is a nice lad," Murat told BBC.

There are some reports that say that the other suspects set to be questioned include three workers from the Ocean Club in Praia da Luz who have been linked to a string of burglaries in the area before Madeleine's disappearance.

There is still no official statement made by either the Metropolitan Police nor officers in Portugal regarding the individuals set to be interrogated.

Scotland Yard had this to say about the search for three-year-old McCann who has been missing since 2007, "[There is] still a substantial amount of work yet to be completed in the coming weeks and months. This recent work is part of ensuring that all lines of inquiry are progressed in a systematic manner and covers just the one hypothesis that she was killed and buried locally. This is the same as would be done in the UK for a murder or high-risk missing person inquiry."