The mother of the man identified as “Jihadi John” recognized immediately from his voice that her son was the alleged killer when he appeared in his first beheading video in August, Kuwaiti government officials told ABC News.

The father of Mohammed Emwazi, who was questioned recently in Kuwait, told authorities the family last heard from his son in mid-2013 when the younger Emwazi called them from Turkey. Emwazi said he was going to do humanitarian work in Syria, the father said, according to the officials. Emwazi’s father, a former policeman, said he’s been waiting for news of his son’s death ever since.

Instead of doing humanitarian work, Emwazi allegedly linked up with ISIS and has appeared in videos online apparently beheading Westerners, including several who were actual humanitarians. Late Tuesday, a British newspaper reported Emwazi’s father had denied the Kuwaiti officials’ claims that his wife recognized their son’s voice in the videos.

The FBI said in September it had identified the black clad figure known in the media as “Jihadi John”, but the identity was kept secret until it was reported last week.

Read More: GoodMorningAmerica