Police in Portugal have acknowledged for the first time that missing Madeleine McCann may be dead.
Speaking to the BBC, one of the detectives leading the investigation said new evidence had given "intensity" to the possibility she was killed.
Chief Inspector Olegario Sousa said Kate and Gerry McCann were not being considered as suspects following recent rumours they were under suspicion.
Madeleine vanished 100 days ago in the Portuguese resort of Praia da Luz.
Mr Sousa said renewed searches by detectives with British sniffer dogs have revealed clues which could point to Madeleine's death.
He was referring to traces of blood found inside the apartment room where Madeleine was sleeping, which are now being analysed by forensic scientists in Britain.
A service was held marking 100 days since Madeleine vanished
Mr Sousa refused to confirm or deny reports in Portuguese newspapers that the sniffer dogs had detected odours of a dead body that had been in the apartment.
The police spokesman made it clear that other lines of inquiry have not been ruled out.
He said Kate and Gerry McCann and their friends who had been on holiday with them were not being treated as suspects.
And he said witnesses might be interviewed again depending on the results of the forensic tests.
'Journey of hope'
Under Portuguese law, police are not normally allowed to speak publicly about the details of an investigation.
A spokeswoman for the McCann family said: "It is obviously heartening that the police in Portugal have finally confirmed that Kate and Gerry McCann are not suspects following the hurtful and unhelpful comments that have been made this week.
"Kate and Gerry understand that the police in Portugal are working hard to do everything in their power to find Madeleine McCann.
"They continue to hope and pray that Madeleine is still alive."
Mr Sousa spoke after Kate and Gerry McCann attended a church service marking 100 days since Madeleine's disappearance.
The church of Nossa Senhora da Luz was packed with holidaymakers and locals, many wearing green and yellow to symbolise hope.
A piper in Glasgow and Madeleine's grandmother Eileen McCann
Kate McCann asked the congregation to "stay with" her and her family as they continued their "journey of hope" and to keep Madeleine in their prayers.
When the couple came out of the church they were greeted by loud applause from waiting holidaymakers and residents.
In recent days they have been forced to deny allegations they were somehow involved in Madeleine's disappearance.
Francisco Pagarete, the lawyer of the only suspect in the disappearance Robert Murat, has criticised her parents' alleged "strange" behaviour on the night she vanished.
Madeleine's grandparents Brian and Susan Healey manned a stall in the city centre of Liverpool, where they live, on Saturday asking for donations.
Mrs Healy, 62, said, "It's been very hard this week."
There are also prayers and pledges of support being said on Saturday by sports stars, including England rugby star Jonny Wilkinson, jockey Frankie Dettori and Everton Football Club.
Teams in the Premiership have been wearing T-shirts with Madeleine's image during their pre-match warm ups.
Among the international events is a Mass being held in the pilgrimage town of Lourdes, France.
And a lone piper played a specially written lament for the missing girl at an international bagpipe event in Glasgow.
The four-year-old disappeared from the apartment room at the Praia da Luz resort on 3 May while her parents were eating with friends at a nearby restaurant.