If the click is from a weapon's hammer being drawn back as a warning, it could indicate that the perpetrator is truly familiar with the weapon.You could point a classic 1911 at someone and click back the hammer as a threat, yes. IMHO you probably don't. It's not how you actually shoot it and you have to assume they won't know you're doing it wrong.
This could well imply an older perpetrator with a longer familiarity with fire arms- and in the case of a semi automatic, historic fire arms.
As you stated, one would not need to pull the hammer back to fire the Browning design. Rather, to get the hammer in that position, I believe one would need to load the pistol, charge it, then pull the trigger while carefully riding the hammer forward. Then, upon seeing the victims, pull the hammer back manually with their thumb.
Its unfortunate that the click sound cannot be traced to that of a pistol's hammer being cocked. If so, it could tell alot about the perpetrator.
A younger perpetrator would be less likely to have that type of weapon. Likewise, a younger perpetrator who had access to Grandpa's pistol would not likely know the quirky hammer features.