Vickrum Digwa, who was jailed for life for the murder of Henry Nowak, is seeking to appeal against his conviction and sentence.
Digwa was sentenced to a minimum of 21 years in prison in June after fatally stabbing 18-year-old Mr Nowak in Southampton on 3 December last year.
His sentence was referred to the Court of Appeal as "unduly lenient" by the Solicitor General, Ellie Reeves, last month.
However, the Court of Appeal confirmed on Friday that Digwa is seeking to appeal against his conviction and sentence.
No date for the hearing of the appeal or the bid to increase the sentence has been set, and no details have been provided about Digwa's challenge.
After stabbing Mr Nowak, Digwa lied to police, saying he was the victim of a racist attack.
The case sparked protests after police body-worn footage was released showing officers failing to administer first aid, instead handcuffing Mr Nowak as he lay dying, despite him telling officers he couldn't breathe.
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The victim's father, Mark Nowak, said the difference in the way the killer and his son were treated was "unbearable" after Digwa was sentenced at Southampton Crown Court.
Prime Minister Sir Keir Starmer said that there were "serious questions" to answer about the case the following day.
The Independent Office for Police Conduct said on Wednesday it is investigating two officers for potential gross misconduct, including potential failures to realise that Mr Nowak required urgent medical attention, and to take action when he said he had been stabbed and could not breathe, as well as the decision to arrest and handcuff him instead of providing first aid.
It was also revealed that one of the officers is under investigation for potentially breaching conduct standards by dismissing Mr Nowak's claim he had been stabbed.
The watchdog is also looking at whether race or religion were factors in the officers' decision-making.
(c) Sky News 2026: Henry Nowak's killer appealing against conviction and sentence
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