The mother of the ISIS terrorist identified as "Jihadi John," reportedly recognized her son's voice when he first appeared in an ISIS execution video last summer.

According to The Telegraph, Ghania Emwazi screamed, “That is my son!,” when she watched the video of a masked Mohammed Emwazi beheading captured American journalist James Foley.

But his mother reportedly did not contact authorities about him at the time. He has since appeared in at least five subsequent execution videos released by ISIS.

The Telegraph reported:

Mr Emwazi Snr was questioned along with one of his sons for most of the day on Sunday after being summoned by police.

"The mother recognised the voice and she screamed 'that is my son' while he was talking before beheading the first American hostage," a source familiar with the Kuwaiti investigation said. "When they played the video again, the father was sure it was his son."

Insiders described Mr Emwazi as "emotional and upset at what had happened to his son" while talking to investigators.

"I am waiting day-by-day to hear about his death," he is said to have told his interrogators."

Report: ISIS Terrorist 'Jihadi John' Is Londoner From Well-to-Do Family

Chilling New ISIS Video Shows Children Being Trained at Jihadi Camp

3 Alleged ISIS Recruits Arrested in NYC; One Offered to Kill Obama

DETAILS: Iran Reportedly Operating 'Secret' Nuclear Sites

Gretchen's Take: Will Any Christians Be Left in Middle East When ISIS Is Done?