Gun safety advocates are urging Maine lawmakers to ban so-called ghost guns like the one used in the Dec. 4 killing of the UnitedHealthcare CEO in Manhattan.

Ghost guns are firearms that are assembled by using kits or parts produced by a 3D printer. They are often untraceable because they lack serial numbers, making it easier for people who are prohibited from possessing a firearm to obtain one.

The use of ghost guns in crimes has increased by more than 1,000% since 2017, according to a U.S. Department of Justice study released in 2023. The most recent example was when 26-year-old Luigi Mangione allegedly used a ghost gun to kill UnitedHealthcare CEO Brian Thompson.

The Maine Gun Safety Coalition is calling on the Legislature to ban ghost guns when lawmakers return to Augusta next month.

“I don’t see any reason for manufacturers to market unserialized gun components other than to allow purchasers to circumvent the law,” Nacole Palmer, the coalition’s executive director, said in a statement.

Fifteen states have banned ghost guns, including Massachusetts and Rhode Island, according to Everytown for Gun Safety.

“No matter who you are or what your views are,” Palmer said, “I think all of us can agree that there isn’t ever a good reason for a company to sell firearm components explicitly marketed as unserialized and untraceable.”

Palmer said she has spoken to two lawmakers interested in sponsoring the bill, but she would not name them. The deadline to file new bills is Jan. 10.

In October, Rep. Vicki Doudera, D-Camden, told the Press Herald that the Legislature’s gun safety caucus, which she founded and co-chairs, was considering sponsoring a bill to regulate ghost guns in 2025.

Laura Whitcomb, president of the Gun Owners of Maine, said in a written statement that the proposal will do nothing to curb crime because criminals aren’t inclined to follow the law and don’t care about rules on background checks, obtaining a firearm illegally or using a firearm without a serial number.

“It is typical for those who would seek to restrict the rights of responsible gun owners to resort to emotional pleas designed to cause fear in Maine residents,” Whitcomb said.

“Maine and United States citizens have been making their own firearms for centuries. Using made-up terms in an attempt to convince elected officials to remove the rights of responsible gun owners is nothing new, and we feel confident that the Maine Legislature will see any proposed bans on ‘Ghost Guns’ for what it is: emotional rhetoric devoid of facts and logic.”

Previous efforts to ban ghost guns proved unsuccessful. Maine has a strong tradition of hunting and responsible gun ownership, though gun safety advocates continually highlight the state’s high rate of suicides by firearms.

In 2021, lawmakers voted down a bill sponsored by Rep. Sam Zager, D-Portland, that would have banned the manufacturing, import, sale, transfer and possession of most undetectable and untraceable firearms in the state, as well as prohibiting the dissemination of downloadable gun codes to manufacture such firearms.

At the time, the Sportsman’s Alliance of Maine opposed the bill, saying that a ghost gun bill was being taken up by Congress and President Biden had made regulating them a priority.

In 2022, the administration cracked down on ghost guns, saying they’re subject to the same rules as commercially sold firearms and requiring components in gun kits to have a serial number, allowing them to be traced. The law was challenged by gun rights groups. The U.S. Supreme Court heard arguments on Oct. 8 but has not issued a decision, though observers believe the court will uphold the rules.

Despite holding majorities in both legislative chambers in Maine and getting support from Attorney General Aaron Frey, the 2021 bill failed 76-67 in the House and 23-12 in the Senate.

A similar bill failed in 2019.

But Maine lawmakers’ willingness to regulate guns has shifted since the mass shooting in Lewiston last year in which a gunman killed 18 people and wounded 13 others.

Last session, lawmakers bolstered background checks for advertised private sales and adopted a three-day waiting period on all firearms, proposals that previously had been considered and rejected. The waiting period is being challenged in federal court.

Lawmakers also approved a ban on rapid-fire devices, like bump stocks. But that bill was vetoed by Gov. Janet Mills and the U.S. Supreme Court in June struck down a federal bump stock ban adopted by the first Trump administration in 2018.

Mills spokesperson Ben Goodman noted that gun reforms introduced and signed by the governor last session represented the most comprehensive package of public safety reforms in recent Maine history. Mills is open to discussing ways to regulate ghost guns, he said.

“Current Maine law makes it a felony to possess or transport a firearm with an altered or obscured serial number,” Goodman said in an email. “The governor would welcome a discussion about updating the existing statute to address the problem of firearms that do not carry a serial number.”

Palmer said online retailers are skirting the rules by selling incomplete frames that can be easily assembled at home.

Palmer, whose group is also leading a citizen referendum drive to make it easier for family members to restrict access to firearms for someone who is deemed a threat to themselves or others, said Maine should pass a law ensuring that the finished firearm has a complete serial number, though the group has not released a detailed bill.

“Ghost guns are a threat to Maine communities, and we urge our state lawmakers to take up this vital issue in the upcoming session,” she said.