A Mississippi man accused of fatally shooting two police officers has mental problems and is addicted to drugs, appearing high in photos after he was arrested, his mother said Monday.

Mary Smith told The Associated Press that her son smoked synthetic marijuana known as "spice" daily and had been hearing voices ever since he was attacked and hit in the head with a pipe several years ago.

Smith's son, 29-year-old Marvin Banks, was charged with two counts of murder in the deaths of officers Benjamin Deen and Liquori Tate. The officers were slain Saturday night in what authorities have so far only described as a traffic stop gone awry.

A preliminary investigation indicated Deen had pulled over a vehicle for speeding and then called for backup, which is when Tate arrived. Gunshots erupted in the road near the Hattiesburg Housing Authority office. Banks' girlfriend, Joanie Calloway, was also charged with two counts of murder.

His younger brother, 26-year-old Curtis Banks, is charged as an accessory to murder and Marvin's friend Cornelius Clark is charged with obstruction. It's not clear what warranted those charges.

The four suspects are set to make their initial court appearance Monday afternoon.

Warren Strain, a spokesman for the Mississippi Department of Public Safety, said it was too early to say who shot the officers or how many shots were fired, and it wasn't clear what prompted the gunfire.

More than 1,000 people filled a hall at the Hattiesburg convention center. Workers initially set up 800 chairs and many more were needed: Hundreds of people stood along the walls and spilled out into the lobby.

With photos of the uniformed men projected above the stage, Mississippi Gov. Phil Bryant — himself a former police officer — said the city was enduring a difficult, sad time.

"We will persevere, we will prevail," he said.

Smith told AP that she has no doubt that Marvin killed the officers. She said he looked high in photos after his arrest.

"You could tell something was wrong with him," she said, speaking on the steps of the Forrest County Courthouse, where she had come to find out more information about her sons' arrest. "I hate it for these families that he wasn't in his right mind."

Marvin and his 6-year-old son lived with Smith, who works the night shift at a nursing home. She said she was resting before work when she got a call Saturday night that two officers had been shot and that Marvin, who is known by "Big Boy," was involved.

After that, Curtis called and said he had nothing to do with it and had been at his apartment at the time of the shooting.

Smith said Marvin was attacked several years ago by a man who hit him in the head with a pipe. The reason for the attack wasn't clear, but he spent time in intensive care and has had problems ever since.

She said she repeatedly urged him to get help for his drug addiction and apparent mental illness, but he wouldn't go.

Katie Walmon, the mother of Marvin's son, said he changed after his head injury and drug use.

"After that, he said he was hearing voices in his head. I say it was the devil," she said.

Smith said she was trying to get lawyers for both of her sons. She said after Curtis' arrest, he complained to her that officers had kicked him repeatedly, stripped him of his clothes and were holding him in cold cell. She has not talked to Marvin since his arrest.

Their initial court appearance is set for Monday afternoon.

Smith said officers often stop young black men without cause in Hattiesburg, sometimes simply to ask them what they are doing.

"The way police here in Hattiesburg harass young black men, you could tell something was going to happen, but I never thought it would be my sons," she said.

Police didn't immediately respond to a telephone call Monday.

Attorney General Loretta Lynch said Monday that the officers' deaths "is made even more tragic by the fact that, on the day they were killed this past Saturday, the country began observing Police Week - a time when we pause to remember and honor the more than 20,000 law enforcement officers who have been killed in the line of duty."

Strain said Marvin Banks also was charged with one count of being a felon in possession of a firearm and with grand theft for fleeing in squad car after the shooting.

"He didn't get very far, three or four blocks, and then he ditched that vehicle," Strain said.

Deen, 34, is a former "Officer of the Year" in Hattiesburg. He is married and the father of two.

Family spokesman J.T. Taylor said he would want his friend of more than 30 years to know that he was going to take care of his family.

Tate, 25, graduated from the police academy last year.

Tate grew up in Starkville, 150 miles north of Hattiesburg. Strain said he was a 2014 graduate of the law enforcement academy. He grew up wanting to be a policeman.

The Associated Press contributed to this report