A man with a “weapon obsession” has been jailed for life for murdering a university student with a “large Sikh dagger” that he claimed to be carrying for religious reasons.

Vickrum Digwa, 23, who stabbed 18-year-old Henry Nowak five times, will serve at least 20 years before being eligible for parole.

When police arrived at the murder scene in Southampton, Digwa falsely claimed Nowak had racially abused him and knocked his turban off, causing officers to arrest and handcuff the student before they saw his fatal injuries.

Hampshire police have apologised for their actions, which received global attention after being criticised by the owner of X, Elon Musk. The police watchdog, the Independent Office for Police Conduct, is investigating the incident.

Speaking outside court, Nowak’s father, Mark Nowak, criticised how police had treated his son, whom he described as friendly and inclusive.

He said: “Henry did not die with dignity. He did not die with the care he deserved. We hold Vickrum Digwa solely and 100% responsible for the brutal murder of our son. But Henry should not have died on the streets of Southampton in police custody. The way he was treated was inhumane and degrading.”

He added: “We are calling on the government to treat knife crime as the national emergency that it is.”

Sentencing Digwa, Judge Mousley KC told him: “You have brought shame on your family, your community and your religion. Your actions have stirred up racial tension, which has made many Sikhs worried about their safety.”

The judge described Nowak as principled and full of promise. On the night of the attack, he was alone and unarmed.

Mousley said that as they approached each other Nowak asked Digwa if he was a “bad man”, possibly because he had spotted him carrying what the judge described as a “large Sikh dagger” – an unusual sight for an 18-year-old non-Sikh.

The judge said Digwa may have felt he was being disrespected, but added: “I am sure Henry said nothing racist.”

The prosecution, had told the jury at Southampton crown court that while Digwa was wearing a small kirpan (a ceremonial sword or dagger worn by initiated Sikhs) under his clothing around his neck, which met his religious obligation, he also chose to carry the much larger knife.

Mousley said practising Sikhs were allowed to be in public with a bladed article, but “that privilege brings with it a huge responsibility. It is a fundamental principle of Sikhism that a kirpan is worn as a symbol of religious faith and is never to be carried for an offensive purpose.”

During the sentencing hearing, Nicholas Lobbenberg KC, for the prosecution, described the killing as a “sustained attack on an unarmed man”. He said Digwa was “skilled with weapons, trained with weapons, sleeps with weapons, searches for weapons on his phone”. The barrister said: “He is a man with a weapon obsession.”

Lobbenberg said aggravating features included Digwa being responsible for Nowak dying alone, humiliated and handcuffed.

He said Digwa made videos of Nowak running away and lying injured with close-ups of his face, which was “intrusive and humiliating”. Digwa’s false defence that Nowak was a racist, drunk aggressor added to his family’s grief and loss.

Jeremy Wainwright KC, for Digwa, who is from Southampton, said he had not gone out that night intending to use the knife as a weapon and had no criminal record.

Nowak, from Essex, who was studying finance at the University of Southampton, was attacked as he was walking home after a night out with his football team.

In his victim personal statement, Mark Nowak described taking his son, the oldest of four children, to university a few weeks before he was murdered and helping to set up his room. He said he saw his son for the last time when he returned home to see a pantomime – a family tradition.

He said he felt he had let his son down by not being there to protect him. “I couldn’t help Henry in his final moments.”

Nowak’s sister Olivia told the court that her brother had lit up every room, and 650 people had attended his funeral. “My life will never be the same without my best friend,” she said. “He was part of me. I lost a lot of myself when he died. He deserved to grow old and start a family of his own.”

His mother, Lucy Ross, recalled her son “beaming” when he told her he had got a place at university. “We speak about Henry every day and we always will,” she said. “He will always be loved beyond words. We will carry this grief for the rest of our lives.”

The Sikh Federation said the Sikh community faced abuse during the trial and there had been misunderstanding about the kirpan. It said: “We want to make absolutely clear the law only provides fully practising Sikhs with a defence under the law to wear a kirpan for religious reasons.”

In the UK it is lawful for a person to possess a kirpan for religious, ceremonial, sporting or historical reasons.