A Danish man convicted of torturing and murdering a Swedish journalist on his homemade submarine has been given a 19-month sentence for his attempt to escape from prison.

Peter Madsen was quickly apprehended on October 20 near the Herstedvester prison in suburban Copenhagen – where he is serving a life sentence for the killing of Kim Wall – after he threatened staff with a fake gun and fake explosives.

The conviction does not matter in reality as it will not be added to the life sentence. However, it may play a role if Madsen at some point makes a probation request. Madsen, 50, accepted the ruling.

Before the verdict was announced, Madsen told the Glostrup City Court in suburban Copenhagen that he wanted to flee because he considered the prison conditions poor, according to the Ekstra Bladet tabloid newspaper.

Madsen, one of Denmark’s most notorious criminals, was captured about five minutes after the escape and less than half a mile from the prison. Staff who followed him saw that he had jumped into a passing white van and informed police.

He used a fake hand gun and mock explosives he had made in jail as he threatened his way out of prison. Madsen told the court that his plan was to hijack cars, take the owners’ mobile phones and move south and eventually reach Germany.

In 2018, Madsen was sentenced in the Copenhagen City Court to life in prison for killing Ms Wall, a 30-year-old reporter from Sweden whom he lured aboard his homemade submarine the previous year with the promise of an interview. He dismembered her body and dumped it at sea.

Madsen later lost his appeal, shortly after apologising to the victim’s family who were present in the appeals court. The sensational case has gripped Scandinavia.

Madsen denies murdering Ms Wall. He claims she died accidentally inside the submarine, but he has confessed to throwing her body parts into the Baltic Sea.

Life sentences in Denmark usually mean 16 years in prison, but convicts are reassessed to determine whether they would pose a danger to society if released and can be kept longer.

Ms Wall had planned to interview Madsen — a self-taught engineer — for a story on a rocket programme he founded in 2014, with the goal of building a crowdfunded rocket to launch himself into space. But by the time he finally responded to her, his cash flow had dried up and he had cancelled the planned test launch.