The three suspects charged in connection with the December 29 killing of Oakland Police Officer Tuan Le made their first court appearance together on Thursday, and all three entered not-guilty pleas.

Mark Demetrious Sanders, 27, Allen Starr Brown, 28, and Marquis Cooper, 34, have all been charged with the murder of Le, who was shot while working undercover investigating a burglary at a cannabis dispensary near Jack London Square.

A fourth suspect, 30-year-old Sebron Ray Russell, has been charged in connection with the burglary but not the murder. Sanders's mother was also arrested on suspicion of being an accessory after the fact, but she has since been released pending formal charges.

Sanders and Brown both previously made court appearances in the first week of the new year, following their arrests shortly after the killing. Cooper was just apprehended last weekend by U.S. marshals in Orange County.

As NBC Bay Area reports, all three entered not guilty pleas in their court appearance Thursday morning.

Le and another plainclothed officer were on the scene of a burglary at Peakz cannabis dispensary on the 400 block of Embarcadero in Oakland on the morning of December 29. A second burglary allegedly took place at the same location that morning, and when Le and the other officer attempted to intervene, their pickup truck was allegedly shot up by Sanders, whom police have identified as the gunman.

The other officer suffered non-life-threatening injuries, while Le died from his wounds.

Sanders, Cooper, and Russell are all still on probation for a 2021 residential burglary conviction, stemming from the burglary of a Pittsburg home with the intention of stealing cannabis plants.

Sanders previously did time for a conviction as a juvenile, for the 2014 fatal shooting of 18-year-old Marcellus Perry in East Oakland, to which he pleaded no contest. He served only five of the ten years he was sentenced to, and was released in 2019.

Previously: 27-Year-Old Stockton Man Arrested In Fatal Shooting of Oakland Cop Served Five Years For Another Oakland Shooting

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