Federal US authorities are investigating the death of a black man during what Louisiana State Police described as a struggle to take him into custody following a chase last year, officials have said.

The death of 49-year-old Ronald Greene remains shrouded in secrecy because state police have refused to release body-camera footage related to the May 2019 chase north of Monroe in rural Louisiana.

Officers say it began when Mr Greene failed to stop for an unspecified traffic violation.

His death drew new attention after his family filed a wrongful death lawsuit this year alleging state officers “brutalised” Mr Greene and “left him beaten, bloodied and in cardiac arrest” before covering up his cause of death.

His family said authorities initially claimed Mr Greene died after crashing into a tree but omitted what state police now acknowledge was the “struggle” preceding his death.

The lawsuit, drawing on witness accounts, alleges officers pinned Mr Greene to the ground and used a stun gun on him even after he apologised for leading them on a chase.

His mother, Mona Hardin, said her family has not been able to grieve because so many questions remain unresolved. She said her son had been a well-liked barber who lived in West Monroe and had a “giving spirit”.

“This has gutted our family,” she told the Associated Press. “How do people live with themselves after doing something like this?”

The investigation comes amid heightened racial tensions within Louisiana State Police, an agency that has been plagued by misconduct cases in recent years.

Earlier this month, state governor John Bel Edwards, a Democrat, said it was “unacceptable” that state police had failed to discipline an officer recorded using a racial slur on duty.

The handling of Mr Greene’s death has eroded the agency’s credibility further, said Eugene W Collins, president of the Baton Rouge branch of the National Association for the Advancement of Coloured People.

“The public has a right to know what happened to Mr Greene that day,” he said, “and the concealing of this information by the Louisiana State Police is not only disgusting but immoral.”

State police spokesman Captain Chavez Cammon said the force is “co-operating with federal officials” even as it conducts its own internal investigation.

Two officials familiar with the case said state police are investigating whether one of the responding officers improperly turned off his body camera during the arrest.

Mr Edwards “is aware of the investigation and expects that there will be a comprehensive and fair evaluation of the facts”, spokeswoman Shauna Sanford said.

Mr Greene’s death was ruled accidental and attributed to cardiac arrest, said Renee Smith, the Union Parish coroner who was not in office when that determination was made.

She said her office’s file on Mr Greene attributed his death to a car crash and makes no mention of a struggle with police.

“The physical evidence we’ve been able to review is inconsistent with the manner of death that they’ve described,” said Lee Merritt, a prominent civil rights lawyer representing Mr Greene’s family.

Local prosecutors did not bring charges against the responding officers but referred Mr Greene’s death to the US Justice Department for a civil rights investigation, said Laurie James, first assistant district attorney in Union Parish.

State police have released few details about Mr Greene’s death. A crash report said officers attempted to pull him over for an unspecified traffic violation shortly after midnight on May 10 2019, about 30 miles south of the Arkansas border. Mr Greene “refused to stop”, the report said, and “a pursuit ensued”.

A single-page report released by the state police said the chase ended when Mr Greene crashed his vehicle.

“Greene was taken into custody after resisting arrest and a struggle with troopers,” the report said, adding that he “became unresponsive” and died on the way to hospital.