William Green's family demanded "prompt and thorough justice" in his death after court documents said he was fatally shot by a Prince George's County police officer.

OXON HILL, Md. — The family of William Green, who police said was fatally shot by a Prince George's County police officer, expressed sorrow and outrage during a news conference Thursday that their loved one was killed after court documents and officials said he was handcuffed in a Prince George's County police officer's cruiser.

Prominent civil rights attorney Billy Murphy, who also represented the family of Freddie Gray after his death sparked days of violence in Baltimore in 2015, is representing Green's family. He spoke to the public Thursday morning, saying the family wants justice after the sudden loss of their loved one.

Murphy said he's never seen such swift action by a police chief: Cpl. Michael Owen was charged with murder on Tuesday, one day after the fatal shooting.

Known as 'BooBoo' to his family, Green was killed Monday night. He was handcuffed inside a police cruiser after Prince George’s County police officers responded to reports that a driver had struck multiple vehicles near the Temple Hills community, court documents said.

A bystander blocked in Green's car while waiting for authorities when Owen and another officer arrived, police said. The second officer has only been identified as "Witness 2" in charging documents. The exact details of the incident remain unclear, but here is what court documents allege happen.

"This is not right," Green’s mother, Brenda said during the press conference. "Something has to be done."

Green's daughter, also named Brenda, said her father was her best friend and they spoke frequently.

"I dreamt of the day my daddy could be able to walk me down the aisle, and I wanted him to be able to meet his future grandchildren, but day won’t ever come now," she said.

Green was handcuffed and sitting in the front of a police vehicle when he was shot multiple times by an officer, police said. Officials said that Owen fired his gun seven times. It's unclear how many of those shots struck Green.

Prince George's County Police Chief Hank Stawinski walked back several statements that Prince George's County media relations representative initially said Monday evening following the shooting.

"We do not believe PCP was involved. We do not have independent witnesses that observed a struggle and we do not know for certain that Mr. Green was seat-belted in that cruiser," Stawinksi clarified.

Charging documents said police searched Green's vehicle and Owen's police cruiser and found no weapons. They were unable to find any evidence indicating that there was a fight that ensued between the two.

Charging documents said police searched Green's vehicle and Owen's police cruiser and found no weapons. They were unable to find any evidence indicating that there was a fight that ensued between the two.

In Owen's bond hearing, Prince George’s County District Court Judge called him "a threat to public safety," citing accusations that Owen fired seven times at the victim.

The victim was "absolutely no threat to [Owen]" Joy told the judge.

Joy said Owen should not be released into supervised home detention because the suspended officer shares a home with another active-duty officer and guns are present in the home.

Meanwhile, Prince George's County State's Attorney Aisha Braveboy promised transparency and accountability as the official investigation unfolds "thorough an independent investigation."

Braveboy went on to say that she will "vigorously pursue justice in a way that is fair and responsible."

Owen was not wearing a body camera, according to police. He is was placed on administrative leave as the investigation unfolds, police said. Owen was denied bond during a hearing on Wednesday, according to authorities.