Prince George’s County police charged an officer with murder Tuesday, saying he fired seven shots at a man who was cuffed in the front seat of a cruiser with his hands behind his back.

Police Chief Hank Stawinski announced the charges less than a day after the incident, following the department’s investigation. Stawinski said bringing such serious charges against an officer within 24 hours of an incident is “unprecedented” for the department.

“I am unable to come to our community this evening and offer you a reasonable explanation for the events that occurred last night,” said Stawinski, who called the moment the most difficult of his tenure as police chief in the Washington suburb. “I have concluded that what happened last night is a crime.”

He identified the victim as William Green, 43, of Southeast Washington. Green was killed while sitting in the passenger side of a police cruiser in the Temple Hills area.

The details Stawinski presented Tuesday altered the narrative previously shared by police after the shooting Monday night. Police initially reported Green may have been under the influence of PCP, a hallucinogenic that has been associated with violent behavior, and that there was a struggle inside the cruiser before Green’s death.

Stawinski said PCP does not appear to have been involved and he could not corroborate an account by witnesses of a struggle in the cruiser. Green may not have been wearing a seat belt in the cruiser as initially reported, Stawinski said.

Cpl. Michael Owen Jr. is in custody and awaiting a bond hearing, Stawinski said. He is charged with second-degree murder, manslaughter and associated weapons charges.

Owen’s family did not immediately return requests for comment.

State’s Attorney Aisha N. Braveboy said a grand jury will be convened in the case and pledged a thorough investigation.

Owen, who joined the force about 2009, was involved with two earlier shootings, one of them fatal.

Charging a police officer in an on-duty shooting is extremely rare. According to a Washington Post analysis of thousands of fatal shootings at the hands of police nationally between 2005 and 2015, only 54 officers were charged.

Green’s death was not caught on a body camera, prompting an outcry from Green’s family, advocates and some county officials.

“We have a lot of questions,” said John Mathis, whose mother was engaged to Green.

Mathis, 19, said Green was a Megabus luggage loader who was slated to be promoted to dispatcher Tuesday. Mathis said Green has two adult children. Green attended the Temple of Praise Church in Southeast Washington.

Green’s family hired Baltimore attorney William “Billy” Murphy to represent them. Murphy represented the family of Freddie Gray, the Baltimore man who died in April 2015 after being injured while in police custody.

“I have seen a lot of horrible fatal police shootings, but this one is in the top 10,” Murphy said in an interview.

Prince George’s County Executive Angela D. Alsobrooks (D) said she has asked Stawinski to review training practices for officers.

“There is absolutely nothing that is acceptable about this incident,” Alsobrooks said.

Braveboy said there are about 80 officers who have body cameras in the Prince George’s Police Department, which has more than 1,500 officers.

“We believe that the public should have that high level of transparency, but we only have what we have,” Braveboy said in an interview.

Stawinski and Alsobrooks both said at a Tuesday night news conference that they supported the use of body cameras. Alsobrooks said their rollout would be funded in the upcoming budget.

State Sen. Obie Patterson (D-Prince George’s), whose district includes Temple Hills, said he was “sort of shocked” to learn the officer was not wearing a body camera when the incident took place.

“It’s a red flag,” said Patterson, who previously served on the county council.

Owen fatally shot a 35-year-old man in 2011 after the man threatened him with a revolver, officials at the time said. In 2009, a person tried to rob Owen outside his home in the Greenbelt area, police said. Owen was off-duty when the would-be robber shot through a hooded sweatshirt he was wearing, according to police officials. Owen, who was not hit by the gunfire, fired back and the would-be robber fled, according to police.

For part of his career following the shootings, Owen served as a spokesman for the department, tasked with speaking to reporters about crimes and answering their questions.

Mathis said the suggestion by police that Green might be under the influence of PCP during the shooting didn’t square with the man he knew.

“That wasn’t like him,” Mathis said.

He said Green had gone out to dinner at a restaurant Monday night and was driving home when the incident unfolded. Police said they were called to Winston Street, near the intersection with St. Barnabas Road, after 8 p.m. for the report of a traffic accident. Witnesses told officers at the scene that Green, who was in a parked car, had struck their vehicle. The officers who approached Green believed he might have been under the influence of a substance, police said.

Green was handcuffed and placed in the front passenger seat of a cruiser while officers waited for a drug recognition expert, police said. Owen got into the driver’s seat and fired a short time later. Authorities are investigating what preceded the shooting.

The Prince George’s County Police Department was the subject of complaints regarding use of force for years in the 1990s, prompting federal oversight that lasted until 2009. But even its critics say the department has dramatically improved in the past decade, incorporating cameras in patrol cars and reporting fewer complaints of excessive force.

The American Civil Liberties Union said Tuesday that Green was “killed needlessly” and condemned the lack of a body camera worn by the officer. The ACLU statement described Green’s death as part of a pattern of Prince George’s County police harming black men in their custody.

The ACLU cited as examples the killing of Leonard Shand, who was armed with knives, by police in Hyattsville last year and the injury of Demonte Ward-Blake during a traffic stop in Oxon Hill.

“It is absolutely senseless for full transparency to not be a number one priority for this department,” the ACLU said. “It should have been a top priority years ago, but these recent tragic events only make this need more urgent.”

Advocates at Casa de Maryland, the state’s largest immigrant advocacy group, pushed last year for a bill to require police to wear body cameras. But that bill did not advance.

In Prince George’s, not all patrol officers are assigned body cameras. One squad per police district has them.

Jorge Benitez-Perez, an organizer with Casa, said Green’s killing demonstrates the importance of police wearing body cameras.

“There is no accountability without transparency,” he said.

Police experts said suspects are most commonly put in the back seat of cruisers, but some departments allow suspects to ride in front, especially if the car doesn’t have a cage separating front and back.

“It used to be you’d never put somebody in the front seat of your car,” said Philip Stinson, a professor of criminology at Bowling Green State University in Ohio who studies police shootings. But some jurisdictions have decided that “you put them in the front of the car because you can keep the closest eye on them.”

Stawinski said bringing charges against Owen was the “appropriate remedy” for the circumstances.

“There aren’t two sets of rules” for those who are and aren’t police officers, Stawinski said. “We are not defending the indefensible.”

Keith L. Alexander, Steve Thompson, Erin Cox, Martin Weil, and Alice Crites contributed to this report.