Portuguese police were questioning several people tonight about missing Madeleine McCann as they searched the home of a British man.
Forensics experts and sniffer dogs were brought in to examine the villa of Robert Murat, just 150 yards from where the four-year-old was abducted.
The Policia Judiciaria said two or three people were being questioned but stressed no-one had been formally arrested.
Intense activity surrounded Murat's house tonight, with officers standing guard outside the property.
Murat has become a regular sight crossing the police tape outside the McCanns' holiday apartment in the village of Praia da Luz since Madeleine's disappearance 11 days ago.
He told reporters he had a daughter the same age as the missing girl who looked very similar to her.
Murat made himself known to journalists on Friday May 4, the day after Madeleine disappeared. He chatted about the case but initially refused to reveal his role.
His mother Jenny, who is believed to own the house being searched, has been running a stall on the seafront appealing for information about Madeleine's disappearance.
Murat, who described himself as half-Portuguese, said he was helping the McCanns as a translator.
But journalists became suspicious about him and went to the Portuguese police with their concerns last week.
Sunday Mirror journalist Lori Campbell reported Murat to local officers as well as to the British Embassy and Leicestershire Police.
She said: "Basically he surfaced on Friday afternoon last week and was walking around as if he was somebody official.
"He claimed that he was just a local guy who spoke fluent Portuguese and English and was helping the family.
"He was coming in and out of the family apartment speaking with the media and acting like he was somebody official. But when questioned about it, he was very vague about his position.
"He said he just volunteered to help the police with their investigation.
"He was in and out of their apartment throughout the week. He said he was just helping to translate witness statements.
"When I was talking to him he was very vague about his purpose. He said he was from the UK going through a divorce back there.
"Asked about what he did for a living, he said he was a property developer, real estate...
"He kept trying to emphasise parts of the investigation such as 'maybe she's gone to Spain, maybe it's too late'."
It is understood the search of Murat's villa started at 7am today and has included draining its swimming pool.
From the front of the house there is a clear line of sight to the apartment where the McCanns were staying.
Chief Inspector Olegario Sousa said more than one person had been taken to the police building in Portimao to make statements.
He emphasised that they had not been arrested.
Local translator Gaynor de Jesus, 32, who went to school with Murat, said she was "shocked" at the development.
She said Murat had joked with her about media rumours that he was a suspect in Madeleine's disappearance.
Ms de Jesus told Sky News: "I do know that he has been the official translator for the police. All witness accounts, everything that's been coming into them, he has had first-hand information.
"He told me that in front of GNR (Guarda Nacional Republicana) officers, who I also know. They said nothing, they laughed and joked, they nodded, they seemed to confirm what he was saying was true."
Dave Shelton, a local expatriate Briton who organised volunteer searches across the area since Madeleine's disappearance, had been due to help organise Murat's mother's stall in the town.
The idea was to gather information from people who otherwise might be unwilling to speak to police.
He said he had known Murat for many years but they had not been particularly close.
"I had a coffee with him on Saturday morning," he said.
"He was telling me how he was working with the Policia Judiciaria and had to sign a declaration of secrecy, or whatever it was, and that he couldn't discuss the case with me at all."
Madeleine was snatched from her bed on May 3 while her parents Gerry and Kate, from Rothley, Leicestershire, were dining in a tapas bar opposite their holiday apartment.
All tonight's activity took place only about 200 yards from where the McCann family is now staying.