A long-time defender of the Second Amendment was shot and killed in what appears to be negligent discharge death at his home involving a young guest.

Maine State Police and Sanford police are investigating the shooting death of Portland Press Herald columnist M.D. Harmon at his home Wednesday afternoon in Sanford.

Police say Michael D. Harmon, 71, died at his home on Brunelle Avenue after a handgun he was showing to a teenage boy went off while the 16-year-old was handling it.

Harmon, a steadfast defender of gun rights and a champion of conservative viewpoints, was a longtime editor and columnist for the Press Herald/Maine Sunday Telegram. He worked for the newspaper for 41 years, and continued to write a weekly column after he retired in 2011.

The teenage boy and his father, both from North Berwick, were visiting Harmon’s home at the time of the shooting, police said. They have been cooperating with the investigation and detectives were expected to question them again Thursday.

Their names are not being released because the shooting is still under investigation, state police spokesman Steve McCausland said Thursday night.

“The circumstances under which the gun was introduced is still under investigation,” said McCausland, who did not know why the gun was loaded. “It is just one of the many questions we have.”

Mr. Harmon’s death appears to be the result of tragic negligence from two people.

A long-time Second Amendment advocate, Harmon should have known to personally unload and chamber-check the firearm in question to verify that it was empty before handing it to the teenager. The teen should have had the basic intelligence not to point a gun at another human being and pull the trigger.

I don’t pretend to know if the investigation will conclude that the Mr. Harmon’s death was an “accident,” as Mrs. Harmon suggests, or if the homicide will be deemed a crime. The fact remains that Mr. Harmon could not have been shot with an empty gun, and if he was showing to to the teenager as the story suggests, then he made a fatal error in not clearing the weapon first. Harmon’s failure to clear his weapon not only cost him his own life; it contributed to a young man becoming a killer, an act that will likely cause significant psychological scarring.

Several supporters of gun control—whom I will not dignify with a link—seem quite gleeful that a staunch advocate of the Second Amendment was killed in such a manner. They’re already holding this up as an example of their theory that, “guns are too dangerous to own.”  The reality, of course, is that firearms are only as safe or as dangerous as they are treated, just like any other complex tool. Complacency kills.

Mr. Harmon is survived by his wife, three children, two stepchildren, and grandchildren.