An autopsy was to be carried out on Friday on the bodies of three women who were found near Greece's border region of Evros on Wednesday with their throats cut.
The motives for the killings remained unclear though police are said to have ruled out theft as the women's personal belongings had not been taken.
A cellphone found in the possession of one of the three is being examined by police for clues that could lead to the perpetrators of the crime.
It is hoped that a DNA test will establish whether the three women were related. One is believed to have been close to 30 while the others were in their early twenties.
The elder woman, who was found at a distance of some 40 meters from the other two, had multiple knife wounds. It is thought that she had tried to escape her attackers.
The other two women both bore a single cut along their throat.
One scenario that police are said to be considering is that the women were executed by human smugglers following a dispute over payment for their transfer over the border.
It is thought that the women might be Syrian though there were was no official confirmation of reports suggesting that this is the case.
Either way, the barbarity of the crime suggests that religious or racial differences might have been an issue.
In a sign of the seriousness of the case, the head of the Greek Police Aristides Andrikopoulos asked top officials of the Thessaloniki Security Police to join the investigation.