Lawyers for the family of Patrick Lyoya, a Black man shot dead by a police officer in Grand Rapids, Mich., said on Tuesday that an independent autopsy showed he was fatally shot in the back of the head by the officer after a struggle during a traffic stop.

At a news conference on Tuesday, Dr. Werner Spitz, the forensic pathologist who performed the autopsy, said that the bullet went through Mr. Lyoya’s skull when he was shot on April 4, and that it was lodged under the skin.

“There’s no question what killed this young man,” Dr. Spitz said.

Reading the autopsy, Ben Crump, a lawyer for the family, said that Mr. Lyoya, 26, was “conscious and aware” that a gun was being held to his head.

“Death was instantaneous when the gun was fired,” Mr. Crump said.

Another lawyer, Ven Johnson, said, Mr. Lyoya’s family wanted to seek “justice through the court system.”

Officials said last week that they were conducting an investigation into the actions of the officer, who has not been named, and that no charging decision had been made. The officer was put on paid leave and his police powers were suspended.

The Grand Rapids police did not immediately respond to a request for comment on Tuesday.

The police released videos last week showing the officer lying on Mr. Lyoya’s back before the officer appeared to shoot him in the head. In the seconds before the shooting, they appear to fight for control of the officer’s Taser.

The videos begin by showing Mr. Lyoya driving in a residential area when an officer pulls him over. Mr. Lyoya steps out of his car, the videos show, and appears confused as the officer tells him to get back in the car.

Police body camera video shows the officer telling Mr. Lyoya that he was pulling him over because his license plates do not match his car. The officer asks Mr. Lyoya whether he speaks English, and Mr. Lyoya responds that he does, adding, “What did I do wrong?”

After a brief exchange about whether Mr. Lyoya had a driver’s license, the officer grabs Mr. Lyoya, who pulls away and starts to run, the footage shows. The officer tackles Mr. Lyoya, yelling, “Stop!” At one point, the body camera footage shows Mr. Lyoya grasping for the Taser in the officer’s hand.

The footage showed that shortly before the fatal shot was fired, the officer yelled, “Let go of the Taser!” Mr. Lyoya is facing the ground and pushing up, with the officer on top of him, in the moments just before the shooting.

A funeral for Mr. Lyoya is scheduled for Friday, the family’s lawyers said.