Justin J. Jackson's family would not deny that he was troubled.

He spent much of his high school years in juvenile custody for assault, weapons and robbery charges as a minor and was convicted of assaulting a neighbor in April 2007.

But they said the 19-year-old had paid for his crimes and worked briefly at a nursing home before his life was cut short Tuesday evening, when a police officer shot and killed him in Mount Oliver after he fatally shot the officer's K-9. Police said the shooting was justified because Mr. Jackson failed to comply when ordered to show his hands and opened fire.

The Pittsburgh Bureau of Police would not identify the K-9's handler, but sources within the bureau said that it was Christian A. Sciulli, an eight-year veteran with the bureau and a member of the Street Response Unit. His dog, Aulf, died at the scene.

According to police, Officer Sciulli and another officer were responding to a call of shots fired in the 1700 block of Arlington Avenue at around 6:50 p.m. when they saw Mr. Jackson standing on the sidewalk about a block away.

Justin Jackson

Both officers got out of the car to ask him questions and ordered him to show his hands because they suspected he had a gun. He initially refused but when he made his hands visible he was holding a gun. Officer Sciulli released the dog to subdue him. Investigators said the officers asked Mr. Jackson to show his hands multiple times, but did not say whether they ordered him to drop the gun.

Mr. Jackson began shooting, hitting the dog twice. Police Chief Nate Harper said yesteday that bullets recovered from the dog were consistent with Mr. Jackson's gun, a .357-caliber Magnum.

The officers, who were not injured, returned fire. Mr. Jackson died of gunshot wounds to the head and chest, according to the Allegheny County medical examiner's office.

"The officers did not realize the dog had been shot until after the incident had ended with both Mr. Jackson and the dog fatally wounded," Chief Harper said at a news conference yesterday evening.

The officers have been placed on administrative leave per department policy pending an investigation.

"Both officers had a horrendous night, having to take a life as well as lose a partner's life," said Chief Harper.

At his parents' house in the West End yesterday, Mr. Jackson's relatives gathered to mourn. In addition to grief, they expressed anger over what they believe was an unjustified shooting. Many family members do not believe he had a gun and theorized that police shot both the K-9 and Mr. Jackson.

Donald James Jackson, his father, said he has witnesses to back up this theory, but he did not want to provide their names yesterday.

He said witnesses told him that they saw one of the officers hover over his son's body and he suspects the officers planted a gun and other evidence there. The family said it wants to look at footage from security cameras in the area to get more information about the incident. Police said they also will review the footage.

Justin Jackson's sister-in-law, Raynelle McCarthy, with whom he lived on Arlington Avenue, said she never knew him to carry a gun because her four children also lived with her.

"He would have never brought guns around [my] kids," she said.

Police refuted the suggestion that Mr. Jackson didn't have a weapon.

"Eyewitnesses, evidence at the scene and trace evidence from the crime lab will prove beyond doubt he had the gun," said Lt. Daniel Herrmann of Major Crimes. Chief Harper said that the gun recovered from Mr. Jackson had been reported stolen in 2006 from a home in Elliott.

The family said even if Mr. Jackson did have a gun, it did not warrant police fatally shooting him. In their view, the officers may have shot Mr. Jackson to make him pay for killing the dog.

Denise Bazemore, his aunt, said she was infuriated at the way the police reacted.

"Is a dog's life worth more than a human life?" she asked.

Lt. Herrmann emphasized that the officers were in Mr. Jackson's line of fire and also were threatened during the incident. The officers acted in response to the gunfire without knowing the dog was hit, Chief Harper said.

Ms. McCarthy was one of the last people to see Mr. Jackson before he was shot. She said he had asked her to braid his hair, and she said she would, before she left the house to pick up a friend and believed he was headed out to the store. When she got back 15 minutes later, someone told her that Mr. Jackson had been shot. She went up the street to see Mr. Jackson lying on his back.

Mr. Jackson had a lengthy criminal history as an adolescent, according to court records. When he was 14, he was charged with aggravated assault and weapons possession and went to a locked-down juvenile facility until he was 16. In April 2005, either while he was completing a day treatment program or shortly afterward, he committed a robbery and once again found himself in juvenile custody, where he remained until June 2006.

The following April, he was convicted of assaulting his neighbor. He also was charged with weapons possession and police alleged that his mother, Anna Jackson, tried to hide the weapon. The weapons charges against Mr. Jackson and his mother were dropped and his father denies there was a gun involved in the fight.

That spring, he began working construction. In January, his mother helped him get a job doing housekeeping at ManorCare, a nursing home in Green Tree. He worked there until two weeks ago, when he decided to go back to construction.

"He just snapped to it," said Mr. Lambert. "Getting in trouble wasn't the right thing so he kind of started realizing that."

Mr. Jackson had planned on going to night school and getting his GED, his father said.

"He decided he wanted to make a change in his life," he said. "At the hands of the city police department, it was taken away."