The DEA agent in question, Lee Paige had a career that spanned over a decade, approximately 14 years before this negligent discharge. He had handled weapons for at least that long with no negligent discharges. So why did Lee Paige have a ND in that room on that particular day? What made a once safe gun handler unsafe?
Public speaking is a frightening thing. More people are afraid of public speaking than any other fear. Most people never get over that fear, they simply learn to control it.
Educating people about firearms safety is not for amateurs, and being in Law Enforcement does not qualify a person to educate others regarding gun safety. Mr. Paige may have been professional enough to handle a "Glock 40", but he wasn't professional enough to be doing so in front of an audience.
If guns are to be handled before an audience, it is imperative that two people clear and confirm the guns are unloaded PRIOR to the speaking event. Then the guns do not leave the speaker/handler's vision thereafter. No ammo should be present. If a gun is found to be loaded, the ammo should be contained and removed from the auditorium. Take it outside to a car. Then, repeat the process of checking. The assistant stays in charge of the weapons afterwards. The guns do not leave his sight. Even so, the speaker should again check the weapon as soon as his hands touch it during the speech. He should stop speaking. He should maintain muzzle discipline. He should open the chamber, look in the chamber and check the magazine's follower if it's an auto or shotgun. He should place a finger on that chamber and follower. Then, he should never put his finger on the trigger. Only when he has again confirmed he is holding an unloaded weapon should he continue speaking.
If you observe Mr. Paige, he did none of these things. His mind was preoccupied with not looking silly due to his inability to speak effectively. He removed his sidearm from it's holster. He opened the chamber of his Glock, and held it for someone across the room to confirm it was clear. He never looked himself.
The gun had an empty chamber but a full magazine. Paige was carrying it like this because he was apparently afraid of a chambered round, and he wanted to be safe. He did not really understand how guns work apparently.
Paige then held the pistol over his head to dramatically release the slide from slidelock. This, of course, chambered the round. Then, after he made his point that he was the only one in the room, that he knew of, professional enough, he nervously placed his finger on the trigger and fired the shot heard around the internet.
Tellingly, Paige informs his supervisor he had a "AD" or accidental discharge. He, to this day, as shown by his lawsuit, has refused to accept responsibility for his actions.
If you are going to speak about gun safety, and handle weapons in front of an audience, you need to be a competent and comfortable public speaker as well as gun handler. Paige was neither. He is lucky he did not kill someone. Remember, if you are going to speak about weapons and handle them during the speech, have a friend you trust and yourself clear and confirm the guns are unloaded prior to the event. I'm talking no more than 15 minutes prior, at the location of the event. Have no ammo in the auditorium. Then, do not let the weapons leave your line of sight. Check the weapon competently as soon as you pick it up in front of the audience. There is no substitute for competence. The nervousness caused by public speaking can strip a person of their competence in handling weapons. Therefore, it is imperative that two people, the speaker and a trusted, responsible, assistant, check the weapons immediately prior to the event. The assistant should remain with the weapons thereafter.
In the end, when it came to handling guns before an audience, Lee Paige just wasn't professino enuff.