Some possible input: I have worked my department's burglary/theft and robbery/homicide detective squads, then ran our crime lab, too. I have been to lots of crime and suicide scenes, search warrants, arrests, etc.
I would guess that suicides outnumber homicides 10 or 20 to 1 in most jurisdictions, and firearms are used in anywhere from 25% to 75% of suicides in any given year and part of the country. Homicide weapons aren't always recovered, while suicide weapons practically always are. I would guess that the big majority of the guns with "bio" tags or blue eaten by blood were used in suicides, not homicides.
A big portion of the other evidence guns are stolen items recovered from criminals, found in search warrants and such, but the police departments are unable to locate the owners/victims to return them, because so few people record the serial numbers of their guns, let alone their other property. If they aren't listed on the nationwide crime data base, NCIC, or matched up through some kind of investigation, the department keeps them and either sells, trades issues or destroys them, depending on where and who.
I kept an informal track on stolen guns mentioned in burglary reports for a good while. In less than 10% of stolen guns incidents (percentage of the guns reported stolen) did the victim find and submit the serial number, either initially or later. The average victim will say something like, "It was a pistol, a Colt or Smith and Weston, some kinda .38. I can tell mine from any others, if you find it, because it has a big scratch on the handle," or some such. A lot of victimized gun owners assume they can call the store where they bought it 10 or 20 years ago and the store can or will find the number and give it to the caller over the phone. Not very likely.
I am sure the percentages of stolen, recorded serial numbers is far higher in places that have gun registration laws, but even in areas like that, some folks didn't acquire the gun in a gun shop or store and/or just never register them.
Man, am I wordy!
I have one gun I know was a suicide gun. It was a scarce S&W, on consignment in a gun shop, put there by the survivors' family, who needed the money. Box and all papers. Dead guy bought it new just beforehand and tested the function by putting one round into the ground first; just shot two rounds in total. It got cleaned promptly, apparently, as there are only 2 or 3 really, really small bare specks where the blue was gone. It had a small "F" carved in the bottom of one grip half. A year later, when I joined the sheriffs office I still work for, I found the "F" was the marking of the detective who handled the case. I don't know why they felt it necessary to 'mark' an item that already had a serial number, but that's the way they did things back then. I remember on Perry Mason episodes, Lt. Tragg often testified, when questioned by D.A. Hamilton Burger, the gun in evidence was the right one because, he always said, "It has my mark on it."
Yes, I am old.
Like others have said, guns have no will of their own, they are neither good nor evil. I am not morbid enough to seek out guns with such histories, but if I want a particular make, model and variation of one, and the price and condition are acceptable, I'd buy it.
and never claimed.
