Trial has begun in western Pennsylvania in the death of an off-duty Pittsburgh police officer shot and killed in a street confrontation more than 3 1/2 years ago.

Christian Bey, 34, is charged with homicide in Allegheny County in the July 2019 shooting that killed 36-year-old Officer Calvin Hall after an apparent dispute at a Homewood block party.

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Family members told the Pittsburgh Post-Gazette that Hall was visiting cousins but decided to leave because a party across the street was getting rowdy. He then returned to make sure everyone was safe after his cousin was threatened by someone with a gun. Hall was shot three times and died three days later. He had joined the Pittsburgh police force two years earlier after previously serving as an officer in Braddock and at Point Park University.

Christian Bey and Calvin Hall side by side

Christian Bey (left), who stands accused of killing off-duty Pittsburgh police officer Calvin Hall during a 2019 block party, went on trial Tuesday. (Allegheny County/Point Park University Police Department)

Deputy District Attorney Stephanie Ramaley told jurors in her opening statement Tuesday that DNA on the murder weapon matched that of the defendant, the Tribune-Review reported. She urged them to focus on the evidence against the defendant and said the slain officer "is not on trial in this case."

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Defense attorney Carmen Robinson said prosecutors hadn't given jurors the whole picture about the fighting and arguing on the street that night. She said the case was about "a rush to judgment and a biased investigation."

Allegheny County prosecutors last month notified the court that they no longer intended to seek the death penalty if the defendant is convicted of first-degree murder.

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Judge Kevin Sasinoski last week denied a defense motion to keep uniformed police officers from attending the trial, or at least limit the number allowed in the courtroom. He also denied other motions to suppress evidence in the case, including data from Bey’s cellphone and Facebook account and his statements to investigators.