Good morning, Bulletin readers. Ghost guns are increasingly showing up at crime scenes, police say. Below, our resident gun expert and West Coast correspondent Alain Stephens rounds up all the essential information (and debunks some misconceptions) about DIY firearms.

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WHAT TO KNOW TODAY

A sailor fatally shot two civilians at the Pearl Harbor Naval shipyard. The gunman opened fire on the Defense Department contractors yesterday afternoon before taking his own life. A third victim was in stable condition at a nearby hospital. It wasn’t clear whether the attack was targeted, said a Navy admiral. “This is certainly a tragedy for everyone here.”

NEW from THE TRACE: A guide to “ghost guns.” Law enforcement agencies are facing a new and growing problem: homemade firearms, colloquially known as “ghost guns,” that can arm people prohibited from owning firearms and confound crime investigators. In our new explainer, Alain Stephens breaks down the basics, including what exactly ghost guns are, how they’re made, the law — or lack thereof — governing them, and why they have some law enforcement officials so concerned.

A coalition of gun reform groups is rating retailers’ gun policies. The group, called Business Must Act, issued letter grades based on the companies’ donations to National Rifle Association-backed politicians, policies on bringing guns into their stores, and gun violence reduction efforts. Earning A grades from the advocates were Kroger and Walmart. McDonalds, Kohl’s, Applebee’s, and Chick-fil-A each scored an F.

An incoming university trustee’s work for the NRA draws scrutiny. Republican strategist Robin D. Roberts runs National Media Research, Planning and Placement and is the incoming president of the University of South Carolina’s alumni association, which gives him a vote on the school’s board. In December 2018, The Trace revealed that National Media’s role in coordinating political advertising by the NRA and the Trump campaign, a violation of campaign finance laws. Both the NRA and National Media have denied any wrongdoing. The State newspaper in Columbia reports that internal critics of the university’s administration are now pointing to our investigation of Roberts’s company as they raise broader concerns about the school’s governance. “This university is already under scrutiny,” said one professor. “Why would they invite more politics?”

Florida’s Republican governor says it’s up to cities to curb gun violence. Ahead of the start of next month’s legislative session, where more than 60 gun bills from both sides of the aisle are pending, Governor Ron DeSantis said his administration was willing to look at giving cities help, but would not “micromanage” local plans for curbing shootings. At the same time, his administration is currently appealing a July court decision that struck down financial penalties for city officials who institute firearm regulations that go beyond state law.

Radiologists on gun violence: “This is our lane, too.” A team of residents at Thomas Jefferson University in Philadelphia looked at data from 110 gunshot patients admitted to city ERs and found that patients shot in the chest or stomach are most likely to return to the hospital. The study’s lead author said creating a database of patient scans could provide radiologists with a unique opportunity for intervention.

A Tennessee man was killed by his neighbor after a feud over lawn care. Davey Roach, 43, took to Facebook to express fears that his gun-owning neighbor, with whom he had argued, would hurt him, and said police hadn’t taken his fears seriously. On November 23, the man fatally shot Roach. In August, Tennessee’s Republican governor rebuffed calls to adopt extreme risk protection orders, which can be used to temporarily disarm persons who present acute threats.