On Monday afternoon, a woman in Bath, Maine, was shot in the head when the gun her fiancé was showing to a prospective buyer discharged in a grocery store parking lot. Chelsea Jones, 22, was sitting in the passenger seat of a silver SUV in front of a Shaw’s supermarket as 23-year-old Dylan Grubbs conducted a private, unregulated gun sale outside the car. The firearm discharged, critically wounding Jones, who has two young daughters with Grubbs. She died three days later.

Federal law requires criminal background checks for gun sales conducted by licensed dealers, but not for person-to-person private sales. According to an upcoming survey of gun owners from Harvard’s Injury Control Research Center, 40 percent of respondents said they’d acquired their most recent firearm without going through a background check. Many unchecked sales look a lot like the one in Bath, where private buyers and sellers make contact through classified ads or online and arrange to meet in parking lots or other public spaces and exchange cash for guns. During these causal transactions, accidents sometimes happen.

In Rapid City, South Dakota, in March, a man was shot in the leg when he handed over one of several guns he planned to sell to a friend and it discharged. At a gas station in Lancaster, Kentucky, in August, a man was shot in the chest while conducting a private sale. Such transfers can be fraught with conflict as well as mishaps. In east Knoxville, Tennessee, last month, two groups of men who arranged a gun sale near a park got into a shootout that left two wounded.

Maine’s gun laws are among the most permissive in the nation: There is no registration of firearms nor licensing of owners, and under a so-called “Constitutional carry” law that went into effect last month, neither a permit nor the training that usually precedes it is necessary for carrying a concealed handgun in public. Although the state’s gun death rate is relatively low, firearms that originate in Maine are routinely found at crime scenes in Massachusetts. A proposed 2016 ballot initiative would require person-to-person gun deals (with exemptions for family members, hunting trips, and cases of “imminent threat”) to go through a licensed gun seller, who would run a federal background check before the parties complete the transfer.

Todd Tolhurst, president of Gun Owners of Maine, told the Portland Press Herald about Jones’s shooting, “This was an accident that happened through negligence or ignorance. People make mistakes and use bad judgment. No amount of universal background check would change that.”

In the 18 states that require background checks on some or all private gun deals, individual gun buyers and sellers subject to those laws either have to go to a gun store to have a background check performed or submit documentation to law enforcement. While there are no laws regulating firearm safety during sales, most gun retailers follow certain rules of conduct and offer basic lessons to customers about how to use a new firearm.

“If you spot unsafe practices happening at a gun store at any time, just go ahead and leave,” a 2012 post on The Shooter’s Log, a blog for gun enthusiasts, advises. For gun buyers, the site recommends, “Do not try your gun in a holster without clearing the gun first. Show the clerk your gun is completely unloaded. The clerk should clear the gun and show you that it is completely clear. Never point a gun at anyone.” In 2013, the blog Concealed Nation advised gun sellers, “Don’t walk [your gun] up to the counter in your hands — bring it into the store in a case.”

On her Facebook page, Jones, who remained in critical condition on Tuesday night, had previously shared her enthusiasm for handguns. Last Friday, she posted a photo of a pink pistol with the words “Come at me Bitch!” printed on the barrel, along with the caption, “um yess!! i WILL have this gun!!” Grubbs is cooperating with investigators, and the intended buyer of the gun was also interviewed by police. No one has been charged in the shooting.

[Photo: Flickr user Clay Larsen]