A retired police captain who died during a night of violent protests in a US state was trying to protect his friend’s pawn shop, his widow said.

David Dorn’s last moments were caught on video and apparently posted on Facebook Live, though the video has since been taken down.

He was killed by people who had broken into Lee’s Pawn & Jewellery, and his body found on the pavement.

No arrests have been made.

His death came on a violent night in St Louis, Missouri, where four officers were shot, officers were pelted with rocks and fireworks, and 55 businesses were burgled or damaged, including a convenience store that burned.

Police also shot and gravely injured a burglary suspect who they say shot at officers.

Cities across the US have seen protests and violence since George Floyd died May 25 after a white Minneapolis officer pressed his knee into Mr Floyd’s neck for several minutes even after the handcuffed black man stopped moving and pleading for air.

Mr Dorn was a friend of the pawn shop’s owner and frequently checked on the business when alarms went off, his wife, St Louis police Sergeant Ann Marie Dorn, told the St Louis Post-Dispatch.

Mr Dorn served 38 years on the St Louis police force before retiring in October 2007.

He then became chief of Moline Acres, a small town in St Louis County.

Former St Louis County police chief Tim Fitch knew Mr Dorn for 30 years and said they became close friends when Mr Dorn and his wife were leading the St Louis police department’s Explorers programme for young people interested in law enforcement careers, while Mr Fitch was leading the county’s programme.

“He was very dedicated to youth, especially disadvantaged youth,” said Mr Fitch, who led the St Louis County Police Department from 2009 to 2014.

“He wanted to see them succeed.

“He wanted to be a role model for those young men and women to go into law enforcement.”

Mr Dorn’s personality was “bigger than life,” Mr Fitch said.

“He was a fun guy, a happy guy.

“You never had to wonder what he was thinking when somebody did something incredibly stupid like a crime because he would just say it as he saw it.”

America Protests Missouri Police Captain Killed
Police investigate the scene of the shooting (David Carson/PA)

When he took over as chief in Moline Acres, Mr Dorn made it clear that his officers would be held to the strictest of standards, Fitch said.

“He wanted them to do the right thing all the time,” Mr Fitch said.

The Ethical Society of Police, which represents black officers in St Louis, said in a news release that Mr Dorn was “the type of brother that would’ve given his life to save them if he had to”.

St Louis police chief John Hayden called Dorn a “fine captain.”

“Many of us, the other officers, looked up to him,” Mr Hayden said.

“Was very well-liked, very pleasant. And his wife still works here.

“So a very sad time for our agency. We will honour him.”