A convicted murderer will be “disciplined” after posting a Snapchat video of himself in prison appearing to “mock” the family of the person he stabbed to death.
Ali Zahawy, 22, was found guilty of murdering Andre Aderemi in Croydon, south London, in August 2016.
A video sent to Mr Aderemi’s mother and seen by the BBC showed Zahawy in his cell saying he was “still banged up”.
The Prison Service said Zahawy would face longer in prison.
Mr Aderemi, 19, was chased around the Monks Hill estate by four men and stabbed 26 times in broad daylight.
Zahawy – along with Rodney Mukasa – was found guilty in May 2017 of Mr Aderemi’s murder following a trial at the Old Bailey.
Both were given life sentences by Judge Zoe Smith and ordered to serve a minimum of 22 years in prison.
Mr Aderemi’s mum, Yemi Hughes, was sent the Snapchat video, which the Ministry of Justice confirmed was recorded inside one of its prisons.
In the video Zahawy swears and says he is still locked up, then adds “but still it could be worse – I could be dead”.
Reacting to the video Ms Hughes – who taught Zahawy at school in Croydon – told BBC London she had a mixture of emotions.
She said: “At first I was really angry by the content of it. It was like he was mocking my son.
“Then I got really emotional – why should I see your face and not my son? Then I felt annoyed.
“I am not for locking them up and throwing away the key, but there needs to be some sort of rehabilitation and some sort of sanction.”
Ms Hughes also called on “better protection for victims’ families”.
She added: “The fact they can video themselves in their cells, what they are up to and how they feel – we should not have to see that.”
A BBC investigation in 2018 found that UK prisons were “awash” with at least 15,000 smuggled phones and SIM cards.
The Prison Service apologised to Ms Hughes for the “distress the video has caused”.
A spokesman added: “We are undertaking cell searches and disciplinary action against Zahawy.
“We are spending an extra £100m on prison security, and anyone found with a mobile phone in prison faces longer behind bars.”