Yamiche Alcindor and John Bacon

USA TODAY

FERGUSON, Mo. — A preliminary autopsy report has convinced the family of Michael Brown that the police officer who shot him should be arrested, a lawyer for the family said Monday.

"His mother asked the questions that ... lawyers could not answer -- what else do we need to get them to arrest the killer of my child?" lawyer Benjamin Crump said at a news conference here.

Crump said Brown's mother, Lesley McSpadden, asked if her son suffered pain before he died. Pathologist Michael Baden, who conducted the autopsy at the family's request, "shared his opinion that he did not suffer," Crump said.

Baden, who also spoke at the news conference, said Brown, 18, was shot at least six times, including twice in the head. None of the bullets entered from the back, and three were recovered from Brown's body, he said.

Brown could have survived all of his wounds except for the shot to the top of his head, Baden said. That shot was probably sustained last, hitting Brown as he was bending over, and exited through his right eye, he said.

Baden said Brown was shot from at least one foot away but the distance could have been as far as 30 feet. Baden said six bullets entered Brown's body and at least two bullets ricocheted and traveled back through his body. Bullet wounds to Brown's arms could have been sustained by putting his hands up or crossing his arms.

Baden said his results could be consistent with police or witness accounts of how Brown died. Crump's position was clear.

"It verifies the worst that the family thinks happened — that he was executed," Crump told USA TODAY. "It confirms what the witnesses said, that this was an execution. That's what the witnesses said from day one.

"It's so hard for his mother and father to even deal with the notion that this is what happened," Crump said. "It's obvious his hands were up at some point because you can tell how the bullet goes from in and out."

Brown was unarmed when Ferguson police officer Darren Wilson, 28, shot him on a street Aug. 9. Witnesses in the area said Brown had raised his hands to surrender when he was shot. The shooting and police response drew racially charged protests that have sometimes turned violent.

Baden said a final autopsy report would require study of the clothes Brown was wearing to see if they contained gunshot residue, which would indicate whether at least one shot was fired at close range. No residue was found on Brown's body, Baden said.

Baden said he also needs eyewitness and toxicology reports.

The St. Louis County medical examiner's autopsy concluded that Brown died of gunshot wounds, but other details have not been released. The Washington Post, citing a person familiar with that autopsy, said the county autopsy indicates Brown was shot six to eight times and had marijuana in his system.

U.S. Attorney General Eric Holder on Sunday ordered a separate, third federal autopsy.

Citing the "extraordinary'' nature of the case, Justice Department spokesman Brian Fallon said Holder directed the action at the request of Brown's family.

The Justice Department is conducting a separate inquiry into possible civil rights violations, related to the shooting. About 40 FBI agents had been deployed to the investigation at the start to assist in canvassing the local neighborhoods for witnesses.

FBI agents also have joined local authorities in some witness interviews related to Brown's shooting after those witnesses expressed doubts about the integrity of the local inquiry, a federal law enforcement official said Saturday.

The official, who is not authorized to comment publicly, said the joint interviews have involved few witnesses so far. But the concerns echo themes from waves of protesters during the past week who have cited a broken trust with local police.

Contributing: Kevin Johnson