A video released earlier this week by the Islamic State group's Libyan branch showed the beheading of another 21 Egyptian Christian hostages.
The four hostages, all members of the same family from the southern Egyptian city of Abu Teeg, were abducted last August while trying to flee the Libyan capital, Tripoli.
Wageh Hakim, whose brother and cousins are being held, told The Associated Press today that the four men were separated from Muslim friends at a checkpoint.