In response to the killing of a Florida teenager by a neighborhood watch captain who maintains that the shooting was an act of self-defense, experts have come forward to once again discourage watch groups from allowing any of their members to carry a gun while on duty.

That advice makes sense. And, indeed, in most locales where watch programs have operated over the past 40 years, that thinking has prevailed.

If it had prevailed in Sanford, Fla., on Feb. 26, 17-year-old Trayvon Martin probably would not be dead, and unrest would not now be sweeping Sanford and communities beyond.

Martin’s death has led to protests in a number of places, including New York, and the escalating anger has led the Sanford police chief to step down temporarily, in an effort to calm the situation.

Meanwhile, the local state attorney has recused himself from the case.

Responding to the shooting, Chris Tutko, director of the Neighborhood Watch program at the National Sheriffs’ Association, said, “First thing: You do not engage. Once you see anything, a suspicious activity, you call the number that the police department has given you.”

It was the sheriffs’ association that launched the watch program four decades ago in response to rising crime, and since then tens of thousands of watches have been formed across the nation, in rural as well as in urban communities.

In both types of communities, the message for watch members has been the same: to not intervene and to not try to be a hero.

Police have the training and skills to properly address situations, and most times they do so correctly. It’s foolhardy for a neighborhood watch member to do more than his or her eyes-and-ears function entails.

While violent incidents involving neighborhood watch volunteers have been rare, they have occurred, and in some cases people have died.

The killing of Trayvon Martin should send a stern message to all such groups, and in communities where volunteers are allowed to be armed, the rules should be changed to prohibit the carrying of firearms.

The Sanford killing also sends the message that no one should be allowed to participate in a neighborhood watch program without first having been subjected to a background check.

Most neighborhood watch programs operate correctly, and there are people in Butler who would feel more comfortable if a visible, effectively operated program were in place here. The Butler Police Department does not have the manpower to give the city the visibility and coverage it needs.

But here or anywhere else, neighborhood watch volunteers should never have a gun in their possession when they are on duty.

“If you carry a weapon, you’re going to pull it,” Tutko said.

And, having pulled it, there’s a good chance it will be fired.

Sanford, Fla., is now dealing with that unfortunate reality, and it’s too early to tell how much fallout from Trayvon Martin’s death will surface in the days ahead.