LOS ANGELES » Two fatal police shootings in the Los Angeles area in the last two weeks began the same way: officers thinking a suspect had a gun.

In one, police say a 14-year-old boy fired at them and they found a weapon. In the other, a 27-year-old man police believed was a carjacking suspect who had fired at them was later determined to be innocent and unarmed.

Different scenarios, same result and, experts say, likely the same outcome once the investigations are completed — police were legally justified to open fire because they had reason to believe the suspects could harm them or others.

“From a legal standpoint, it doesn’t technically matter if he’s armed or not,” said Peter Moskos, a former Baltimore police officer and a criminologist at the John Jay College of Criminal Justice in New York. “It matters if a reasonable cop has a reason to believe he is.”

The killing of Donnell Thompson Jr. occurred after Los Angeles County Sheriff’s Department deputies suspected he had been involved in the carjacking on July 28 in Compton. The department acknowledged Tuesday, however, that investigators had found no evidence connecting Thompson to the crime.

The carjacking suspect fired at deputies during a car chase and ran off when he crashed. Deputies searching for him found Thompson about two hours later after a homeowner about a half-mile away reported a man lying in his front yard.

Thompson fit the general description of the carjacking suspect — a black man between 20 and 30 wearing dark clothing. He didn’t move or respond when deputies repeatedly shouted at him and then used a flash-bang device.

Thompson finally got up when he was shot with rubber bullets and charged at an armored police vehicle about 25 feet away, according to sheriff’s Lt. John Corina.

Thompson was then shot twice at close range by a deputy riding in the turret of the vehicle, one of two dispatched to provide cover for officers, Corina said.

The deputy, a 20-year veteran, said he fired because he feared Thompson was armed and could harm officers behind the other vehicle or citizens if he made it past the deputy, according to Corina.

Thompson’s family believes the department overreacted and that race was a factor. His father filed a civil rights claim against the department alleging deputies didn’t have probable cause to open fire.

Chuck Drago, a former police chief in Oviedo, Florida, with 35 years of law enforcement experience, said the shooting appears justified based on what deputies knew at the time.

“As sad as it is when it turns out to be an innocent person — and it’s a horrible thing — it’s reasonable and justifiable to do that if there’s reason to believe he’s armed,” he said. “That’s the key here.”

In the other fatal shooting, a Los Angeles police officer investigating a graffiti tagging report killed a 14-year-old boy Tuesday after the teen fired at officers during a brief foot chase, Deputy Chief Robert Arcos said.

Police said they recovered a loaded, long-barreled revolver the teen was carrying when he was shot.

The shooting occurred in Boyle Heights, a rapidly gentrifying neighborhood east of downtown Los Angeles that police say is still home to nearly three dozen gangs.

Laurie Levenson, a criminal law professor at Loyola Law School in Los Angeles who has studied police misconduct, said officers are given great legal deference when they use lethal force.

“The law looks at things through the eyes of officers as it occurs, not what you know after the fact,” she said.