While this thread is a few months old,, it's still very important.
Always, always, always assume a gun is loaded until you personally inspect it.
My son, a LEO,, & I were somewhere several years ago. A guy handed me a gun, and I checked it. It was clear. When I handed it to my son,, the guy said; "You just saw him check it for clear!" To which my son replied; "That's my Dad,, and he taught me to always check every firearm, no matter who just checked it. And he'd whip my butt if I DIDN'T check it myself!" I was a proud papa that day.
To clarify something. There is no such thing as an AD (accidental discharge.) It's a ND or negligent discharge. Why the difference? Because someone was negligent in leaving a gun loaded. Someone was negligent in not checking a gun.
In USPSA competition, as a Range Officer running a competitor we have very specific range commands. Once a shooter has finished a stage,, the RO says; "If you are finished,, unload & show clear." The word "if" puts the responsibility on the shooter to make sure they are finished that stage. Once they unload it, and show you it's clear, the command is; "If clear, hammer down, holster." Again,,,, this puts the responsibility BACK on the shooter to assure the gun is unloaded. It's the shooters responsibility to be the last person to verify the gun is empty.
Safety first.
And sadly,, I too have had the occasional situation where a person handed me a gun that they claimed was unloaded,, when it wasn't.