Here is a sampling of shooting deaths in the 48 hours between Tuesday evening, when Barton, police say, ended his wife's life with a hammer and Thursday evening, when he committed suicide in his car at a suburban Atlanta garage.
A police chase around the Washington DC Beltway ends in the death of Merachew Luca Fitigu, 24, who had refused to pull over and sped off towards the state boundary with Virginia, shooting as he went. His car crashes into the central barrier and bursts into flames. Fitigu is found shot dead in the wreckage: it has not been established whether he shot himself or was hit by police.
An insurance executive, Scott Howell, is shot dead in front of his sister and daughters by an intruder outside his parents' home in this prosperous Oklahoma City suburb. The attacker flees in his victim's car. The murder of Howell, a deacon at his church and a Sunday-school teacher, distresses the neighbourhood of Edmond, which has an average of one murder a year.
Police say the gunman "just appeared" in the driveway as Howell and his family were getting out of their car. The sergeant in charge of the investigation says it was: "Boom! No words exchanged; nothing. The suspect fires one round, and it strikes the victim. The sister grabs the kids and flees to the house and summons help. Howell's father called the emergency number, telling the switchboard: 'My son has been shot in the front yard.' As his sister ran for help, the gunman pulled his victim out of the car and accelerated away, left him dying in the driveway."
The killer is described as a slim black male wearing a red bandanna over his face. He may have worn a stocking mask. As well as searching for the gunman, police have yet to establish a motive.
One man is killed and one injured in a shooting at a pawn shop in the Hiltop area. The injured man, manager Andrew Fisher, is in critical condition. The gunman escapes.
A 32-year-old man is found shot dead near his terraced house. No motive has been established and no one has been arrested.
CLARENDON, S CAROLINA
A couple are found dead in their home; 45- year-old Linda Crafton was shot in the face while asleep; her wheelchair-bound partner, James Morris, was found shot dead in his wheelchair. Police say they believe Morris feared Crafton was intent on ending their relationship.
Two people are found dead on Wednesday evening. Police speculate that the killings are a double murder or murder-suicide. The bodies were found by a man dropping off his daughter for a piano lesson.
A man described by police as a drug suspect is shot and critically wounded in an alley in when he tries to flee after they attempt to question him. Police say that as he ran away, he had turned around and fired at them.
Police shoot and kill a suspected car thief after he apparently threatens to shoot them with a semi-automatic after he is caught in the act of stealing a car. Earlier, police had shot at a car similar to the one reported stolen, narrowly missing the woman driver.
Maureen Tavener, 46, a county probation officer is shot dead in her home in Gloucester Township early on Thursday by a former boyfriend, who was a retired Philadelphia police detective.
She dies of multiple gunshot wounds to her head and face.
Her two children, 16 and 17, were at the house at the time of the killing.
Anthony Sansone, 67, called police to his home in Philadelphia less than an hour later and gave himself up. He is charged with murder in New Jersey and in Philadelphia with being a fugitive from New Jersey justice.
One of Ms Tavener's four sisters tells reporters "I wish we could have prevented this. Violence is violence. You hear about it, but it happens to other people. Now, it's us."
According to another sister, Ms Tavener's 16-year-son had pursued Sansone out of the house and punched his hand through the car window in a vain attempt to stop him driving off. Sansone threatened to shoot him if he did not let go.
The murder happened just a day before the whole family was due to leave for upstate New York on holiday.
A 30-year-old man shoots himself in the head after being wounded by police in a city street in Renton.
The man had earlier been seen walking up and down the street outside his house, waving a handgun and pointing it at his head.
When police arrive and try to restrain him, he points the gun at them; they open fire, wounding him, but he dies by his own hand.
Deborah Kucher, a nurse's assistant, and her nine-year old daughter are found shot dead in their flat in the town of Leicester on Wednesday.
Kucher's boyfriend was being sought in connection with the murders. Neighbours told police that Kucher had recently thrown her boyfriend out after complaining of threats of violence.
"Yeah, I'm worried. I have woods around my house, so anything could be possible," says a neighbour. "I'll just wait it out but it's especially shocking to hear a nine-year-old girl was killed."