LOS ANGELES (CBSLA) – A 28-year-old security guard accused of shooting and killing a man at a Walgreens pharmacy in Hollywood last month — who he suspected of shoplifting — pleaded not guilty to murder Thursday.

Donald Ciota appears in Los Angeles County Superior Court on Dec. 31, 2018. (CBS2)

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Donald Vincent Ciota of Covina was arraigned in a downtown Los Angeles County Superior courtroom on one count of murder and an allegation that he used a firearm “as a deadly and dangerous weapon.”

Ciota is charged with shooting 21-year-old Jonathan Hart on the evening of Dec. 2 at a 24-hour Walgreens store located at Sunset Boulevard and Vine Street. Hart was rushed to a hospital, where he died.

Hart, who friends called “Sky,” was allegedly confronted by Ciota. A witness told CBS2 that Hart was carrying something as he walked near the door to use the ATM. The witness said he knew Hart, whom he believed to be homeless and suffering from mental illness.

The confrontation then turned into a physical altercation. As Hart turned around and ran away, Ciota pulled out his firearm and allegedly shot Hart in the back of his neck, according to prosecutors and a coroner’s report.

Ciota was arrested Dec. 28 and remains jailed on $3 million bail. He is being represented by celebrity attorney Mark Geragos.

About one week after the shooting. Hart’s family announced it was suing Walgreens for $525 million.

An undated photo of 21-year-old Jonathan Hart.

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“John was not shoplifting when he was shot,” said family attorney Carl Douglas at a Dec. 11 news conference.

Douglas alleged that Hart was targeted because he was black and gay and questioned why Walgreens only has armed security guards at four stores in the Los Angeles area.

“Each of these stores are in the black, brown and homeless and LGBT communities, and we want to know why,” attorney Carl Douglas said at a Dec. 11 news conference.

Walgreens issued a statement in response, saying the company had “extended our deepest and most sincere condolences” to Hart’s family, and noted that as a result of the shooting, “we immediately terminated the security company” that hired the guard.

The company also said that it has “cooperated with authorities and will continue to support their prosecution of this case.”

“We are committed to providing a safe environment for our employees, patients and customers in the communities we serve,” Walgreens said. “We contract for armed and unarmed security, as well as video surveillance, in our stores based on the public safety needs of each location. We operate in thousands of communities and neighborhoods across the nation and the suggestion that we would inappropriately serve any community is simply false. We firmly believe everyone should be welcomed and treated equally in all of our stores.”

If convicted as charged, Ciota faces a possible maximum sentence of 50 years to life in prison, according to prosecutors. His next hearing is scheduled for Feb. 13.

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. City News Service contributed to this report.)