Former ISIS hostages: No, Sotloff didn't convert; Yes, he fasted on Yom Kippurattacked him for converting to Islam (see the comments to that post).
The New York Times has now interviewed several hostages who were released from captivity by ISIS (now known more widely as Islamic State) and they confirm that Sotloff remained true to his Jewish faith and did fast on Yom Kippur.
Former hostages said that a majority of the Western prisoners had converted during their difficult captivity. Among them was Mr. Kassig, who adopted the name Abdul-Rahman, according to his family, who learned of his conversion in a letter smuggled out of the prison.
Read the whole thing.Only a handful of the hostages stayed true to their own faiths, including Mr. Sotloff, then 30, a practicing Jew. On Yom Kippur, he told his guards he was not feeling well and refused his food so he could secretly observe the traditional fast, a witness said.