Police are awaiting the results of tests carried out on traces of blood recovered from Madeleine McCann's holiday home.
Samples are being analysed at a UK forensic laboratory in an attempt to establish if the evidence matched the DNA of the missing four-year-old.
The traces, found on the wall of the Algarve apartment, were only uncovered this week - more than three months after the British girl disappeared.
It is believed a sniffer dog, brought in by British detectives, located the tiny traces despite attempts to wash them off.
Scientists are hoping to extract DNA from the sample to cross-reference against an example obtained from a toothbrush or hairbrush used by Madeleine.
Friends of the McCann family have expressed their disgust at what they said was a smear campaign against them. Rachel Oldfield, who ate with the McCanns on the night Madeleine disappeared, said some newspaper reports were completely inaccurate.
"I think there are some leaks coming from the police because a lot of what I have read recently has been completely untrue," she said.