The mummies, who lost their heads as yet another casualty of Egypt's political chaos, are unknown ancient Egyptians, officials told Discovery News. Prior to the uprisings that spread across the Arab nation, they had been used to test the CT scan machine in the museum.
Vandalized a week ago at Cairo's Egyptian Museum, where thieves looking for antiquities broke 70 objects, the mummies have become the symbol of the world's concern for ancient Egyptian cultural heritage.
The shocking image of their heads lying on the floor of the Egyptian Museum with broken bones scattered all around have been haunting Egyptologists and mummy experts for a week.
Despite close examinations of the released pictures, extensive archival research and opinion exchange on social networks, no expert has been able to identify them.
"It's starting to take on the hallmarks of a TV drama like 'Bones' or 'CSI.' Just who were the two mummies?" Kate Phizackerley, who runs " Egyptological Looting Database 2011," asked in her blog.
Fear that royal mummies could have been damaged arose with the first news reports of the break-in, which mentioned looters ripping off the heads of two Pharaonic mummies.
Indeed, a gilded, open-work cartonnage case belonging to Tjuya, shown on the museum floor in dramatic footage from Al Jazeera, prompted speculation that the damaged mummies were Yuya and Tjuya, which recent DNA tests identified as King Tut's great-grandparents.
"We all feared they could be Yuya and Thuya, but the pictures proved they weren't," Phizackerley said.
Further information from Zahi Hawass, newly appointed minister of antiquities, did not help solve the mystery.
In an interview with the New York Times on Tuesday, Hawass said that the thieves took two skulls from a research lab before being stopped as they tried to leave the museum.
Wafaa El Saddik, former director of the Egyptian Museum, confirmed to Discovery News that the mummies had been in a research lab.
"These mummies were kept in a special room at the west side of the museum and they were in the university clinic for some research. They are unknown persons," El Saddik, who led the museum until a month ago, told Discovery News.
The new information makes it even harder to guess who the mummies might be.
"They might never have been in display," Phizackerley said.
Researchers were particularly intrigued by one mummy, whose ripped-off head was photographed amid bones scattered across the floor.
"The bones in the picture apparently do not belong to the heads. Quite certainly we are talking of non-royal mummies," Swiss anatomist and paleopathologist Frank Rühli, told Discovery News.
Egyptologist and anthropologist Jasmine Day from Perth, Australia, agrees: "Many of the royal mummies have distinct facial features and even intact hair. The damaged mummies and bones appear to have been knocked accidentally -- or tossed vindictively -- off a table or shelf in the darkened storeroom."
Salima Ikram, professor of Egyptology at the American University in Cairo, confirmed that the mummies were stored in a lab.
"These were Late Period fragmentary mummies that were used to test the CT machine and were stored near the machine. When the people who attacked the museum went in, in the area of the giftshop, they also breached the room in which the test mummy fragments were kept," Ikram, a leading expert on animal mummies, told Discovery News.
Speculation that at least one head had been torn from a complete and well- preserved body came from a picture found online by Mercedes González, director of the Instituto de Estudios Científicos en Momias in Madrid.
The photo completely matched the image of the damaged mummy.
According to the Chilean journal Conozca Más, which published the picture of the complete mummy in 1993, the mummified body was displayed at the Egyptian Museum in Cairo, and then withdrawn.
"By the shape of the forehead and jaw, I believe this is the mummy of a teenage woman. It is interesting that the body has no abdominal incision for evisceration," González told Discovery News.
She agrees with Rühli, head of the Swiss Mummy Project at the University of Zurich, that the bones scattered around the mummified head do not belong to the individual.
"They appear to correspond to an adult. There is no soft tissue on them, while the mummy featured bones which were covered by skin in very good condition," González said.
Regarding the other head, shown on Hawass' website, González believes it belongs to an adult male.
"The nostrils are dilated, due to plugs of linen employed during the embalming, while the white spots may be fungi. This might indicate that the mummy was stored somewhere out of sight," González said.
According to the researcher, the well cut neck might indicate that the head was already loose, torn from its body long ago. Indeed, that was a typical practice of the 19th century.
"It is tragic to see Egyptian mummies treated once more in the cavalier and cruel fashion in which tens of thousands of their fellows were once treated by ancient Egyptian tomb robbers and Victorian souvenir hunters," Day, the author of "The Mummy's Curse: Mummymania in the English-Speaking World," said.
"I never thought I would witness such things in my lifetime," Day said.