The dad of evil Streatham terrorist Sudesh Amman warned him "not to be naughty" less than 24 hours before his rampage, it's understood.
It is believed Faraz Khan, who left the UK three months ago, learned about his 20-year-old son's death through a cousin who messaged him.
Mr Khan, who said he spoke to Amman about religion on Saturday, is reported to be shocked at his son's crazed attack on Streatham High Road in south London - during which he stabbed shoppers at random.
"He's never spoken to me about these kind of things. He would never talk to me about naughty things.
"I heard they found a lot of things and I saw them on the news, but I never thought he would go this far.
"I told him not to be naughty, be good, and he listened," the father said.
Mr Khan told Sky News he was unaware Ammann, of Harrow, northwest London, had become radicalised.
He continued: "He was reciting the Koran to me and he was translating that to me.
"I spoke to Sudesh one day before he passed away. I didn't know he had become radicalised."
Amman's mother Haleema Khan yesterday also told of her shock at how her son brought chaos to the streets of the capital.
She said Amman, a former college student, had asked her to make him a mutton biryani hours before launching his attack.
"He became more religious inside prison, that's where I think he became radicalised," Ms Khan said.
"He was watching and listening to things online which brainwashed him.
"He was a polite, kind, lovely boy. He was always smiling. I'm so upset, he was only 20 years old."
The jihadi was under police surveillance when he stabbed his victims in the suburb.
Wearing a fake suicide vest, he plunged the blade into nursery school teacher Monika Luftner, 51, and another victim.
Armed officers shot Amman dead within 60 seconds of his rage.
Since then, Senior Cabinet minister Michael Gove has said that terrorist offenders should be imprisoned indefinitely "if necessary".
Mr Gove, a former justice secretary, said the Government intended to bring forward emergency legislation this week to end the automatic early release of terrorist offenders.
