A trial begins this week for the man accused of killing retired St. Louis Police Captain David Dorn during the height of summer unrest following the police killing of George Floyd in the summer of 2020. 

Opening statements were made on Monday in the trial of Stephen Cannon, 26, of Glasgow Village, who is charged with first-degree murder in the killing of Dorn, who was protecting a friend's pawn shop during looting on June 2, 2020, the St. Louis Post-Dispatch reported.

Retired police lieutenant David Dorn was killed during the George Floyd riots

Dorn, a retired police captain, was protecting a friend's pawn shop when he was shot and killed by looters. (Missouri Department of Public Safety)

The shooting came on a night of violence across St. Louis after demonstrations sparked by the killing of Floyd by former Minneapolis police officer Derek Chauvin on May 25, 2020.

Dorn and four others were shot, officers were pelted with rocks and fireworks, and 55 businesses were burglarized or damaged across St. Louis during the protests.

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"Along with the unrest that came — that civil unrest — came chaos," chief trial assistant Marvin Teer told jurors Monday. "And St. Louis was touched by it, too. ... Our streets were ravaged with looters, with chaos, a pain set ablaze. With that legitimate pain came acts, many of which are unconscionable."

Dorn, who was 77, served nearly four decades on the St. Louis force before working six years as chief in Moline Acres. His wife, Ann Dorn, said her husband often checked on alarms at the pawn shop because he was friends with the owner.

Car burns during 2020 riots

A car burns at the corner of Martin Luther King Boulevard and Tucker Boulevard on Tuesday, June 2, 2020.  (David Carson/St. Louis Post-Dispatch/Tribune News Service via Getty Images)

Prosecutors have said Cannon was one of several people looting the store that night. When Dorn arrived, Cannon went to a nearby corner, allegedly with a gun in his hand. Cannon was the only person on the corner when shots were fired and Dorn was hit, prosecutors said.

Cannon's attorney, Brian Horneyer, told jurors Monday that no physical evidence linked Cannon to the killing. He also said the state's main witness, who is also charged with several felonies, told detectives he would say "anything" they wanted for a plea deal and to escape a murder conviction.

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The trial is expected to last through the week.

The Associated Press contributed to this report.