A 50-year-old German man was jailed for life Tuesday for shooting dead a petrol station cashier because he was angry about being told to wear a mask while buying beer.

The September 2021 murder in the western town of Idar-Oberstein shocked Germany, which saw a vocal anti-mask and anti-vaccine movement emerge in response to the government's coronavirus restrictions.

The row started when 20-year-old student worker Alex W. asked the man to put on a mask inside the shop, as required in all German stores at the time. After a brief argument, the man left.

The perpetrator — identified only as Mario N. — returned about an hour and a half later, this time wearing a mask. But as he bought his six-pack of beer to the till, he took off his mask and another argument ensued.

He then pulled out a revolver and shot the cashier in the head point-blank.

On Tuesday, the district court in Bad-Kreuznach convicted Mario N. of murder and unlawful possession of a firearm, and handed him a life sentence.

Under German law, people given a life sentence can usually seek parole after 15 years. His defense team had sought a sentence of manslaughter, rather than murder.

At the start of the trial, prosecutor Nicole Frohn told how Mario N. had felt increasingly angry about the measures imposed to curb the pandemic, seeing them as an infringement on his rights.

"Since he knew he couldn't reach the politicians responsible, he decided to kill him (Alex W.)," she said.

Mario N. turned himself in to police the day after the shooting.

German has relaxed most of its coronavirus rules, although masks are still required in some settings, such as public transport.