A white Alabama police officer was charged with murder Wednesday in the shooting death of a black man who, a family lawyer says, was walking home when he was slain outside a neighbor's house.

Montgomery police Officer Aaron Smith, 23, was arrested with bond set at $150,000, Montgomery County District Attorney Daryl Bailey said Wednesday.

"I will do everything in my power to protect a police officer who is operating within the law," Bailey said. "I will also use every ounce of my power to prosecute a police officer who is acting outside of the law."

Bailey wouldn't say what evidence led to the charge in 58-year-old Greg Gunn's death.

Smith posted bail shortly after his arrest. Dressed in a white button-down shirt and a gray sports coat, he held hands with his mother, but did not speak, during a press conference at his attorney's office.

Attorney Mickey McDermott said Smith's arrest is a "political witch hunt" to "quell public unrest."

"This is on the back of a 23-year-old police officer working by himself in a high crime area, with a larger man who ran," McDermott said. "We're sorry for the loss of this man, but he brought it on himself."

Smith comes from a multigeneration law enforcement family, McDermott said. His father retired as a major from the Montgomery Police Department and then went to work for the state alcohol control board and then Alabama Bureau of Investigation. Smith's mother is a former cadet with the Montgomery Police Department. Police officers from across the area helped Smith post bail.

Gunn's death comes amid a national conversation about law enforcement's use of lethal force in minority communities, after multiple cases of black men dying at the hands of police.

The quick move to charge a white officer with murder in the shooting of a black man stood in contrast to past episodes of police violence dating back decades in Montgomery, where a string of confrontations between white officers and black residents kept tensions high in 1970s and '80s.

"In the history of Montgomery, this is not one of our great days," Montgomery Mayor Todd Strange said Wednesday.

Authorities said Smith shot and killed Gunn about 3:20 a.m. Feb. 25.

Police Chief Ernest Finley said Monday that Smith deemed Gunn "suspicious," left his car and approached Gunn on foot. Authorities have not said what Smith found suspicious about Gunn.

The Gunn family's attorney, Tyrone Means, said Gunn was walking home at the time. He said earlier this week that Gunn attended a regular card game with friends on Wednesdays, and he frequently walked from his friend's house to his home a few blocks away, where he lived with his mother.

Authorities initially said Gunn was holding a stick or cane and the two men had struggled. But Gunn's next-door neighbor Colvin Hinson told The Associated Press the stick was actually an extension handle for a paint roller that belonged to him.

"He didn't have anything, other than the cane they was talking about was my paint cane laying right there. Been there two or three weeks," Colvin Hinson said Wednesday.

Hinson said he was awakened by loud banging on his front door before he heard gunshots. He opened the door to see Gunn in the grass beside the stick.

Hinson said he's always felt safe at home and supports law enforcement, but questioned the shooting.

"You know I tip my hat to them because we do need them," Hinson said. "I just want to know if the protocol is to shoot an unarmed man down dead in front of somebody's house anytime they feel like it."

City officials on Wednesday would not confirm if Smith was injured in the incident or if they still believe Gunn was carrying anything. The State Bureau of Investigations will continue to investigate the case, and all findings will be presented to a Montgomery County grand jury.

Bailey said he believes Gunn's death is an "isolated incident," and asked the community not to criticize the city's police department.

"I want to be crystal clear that the arrest that is being made today is in no way an indictment on the Montgomery Police Department," Bailey said. "In fact, 99.9 percent of the Montgomery police officers do an exceptional job on a daily basis protecting us and our community. They are, in fact, the thin blue line between order and chaos."