By Emma Farge

LAUSANNE, Switzerland (Reuters) -A Swiss court on Thursday acquitted six white police officers of charges of negligent homicide in the death of a Black man who suffered a fatal heart attack after he was held down in the street during an arrest.

The case has raised questions about structural racism in Switzerland and the prosecution had compared it to the killing of George Floyd in the United States, who died after an officer knelt on his neck for more than nine minutes in 2020.

Mike Ben Peter, a 39-year-old Nigerian, suffered the heart attack in 2018 after he was kicked and held face-down in a street in Lausanne during an arrest.

Judge Pierre Bruttin described the case as "tragic" but said the officers had to be acquitted based on the evidence which drew on medical experts' testimonials.

The officers had denied the charges, which could have brought a maximum sentence of three years in prison had they been convicted. Swiss privacy laws mean they cannot be named.

Bruttin said Ben Peter's death had been "multifactoral", citing his obesity and the stress of the situation among the factors.

Supporters of the victim's family left the courtroom as the verdict was read out shouting "shame" and "scandal"! Shortly after, about 100 protesters entered the court building booing and shouting "assassin" at defence lawyers and police.

"Police are protected by the state," Amivi Sabine Akassi, one of the victim's supporters, said after the verdict. "Even if there is a crime that's very serious it's always the population against the state, especially for foreigners. It's not right."

CALLS FOR REFORM

Ben Peter's death has led to protests calling for police reform, although defence lawyers dismissed the comparison with the Floyd case.

A group of U.N. experts said last year there was systemic racism in Switzerland in a report that raised serious concerns about "excessive use of force and the expectation of impunity by police" and cited this case. A Swiss government-mandated study acknowledged racism was structural.

According to the indictment, the officers first noticed Ben Peter during a drug patrol after he collected a bag later shown to contain marijuana.

The indictment said he did not comply with police requests and the officers used pepper spray and knee kicks to the ribs and crotch to get him on the ground and handcuff him.

It said he continued to struggle as he was held face-down by officers for three minutes, until they noticed he appeared unconscious. Ben Peter was later pronounced dead after a heart attack.

In an unusual move, the public prosecutor leading the case on Monday dropped the charges against the officers saying they had merely "violated the rules of prudence", Swiss broadcaster RTS said.

The court still had the ability to pronounce a verdict.

"This is extremely unusual and, for me personally, it confirms my concerns about the ability and willingness to prosecute cases involving police officers in Switzerland," Simon Ntah, lawyer for the victim's family, told Reuters before the verdict.

(Reporting by Emma Farge; Editing by Angus MacSwan)