It has been rumored, but never authenticated that this is a photo taken of Billy the Kid and part of the posse that captured him. It is well known that this picture couldn't have been taken at Stinking Springs, because there would have been no photographers present in that area. However it is very possible that Garrett had a picture of him and his posse taken with the Kid once they arrived in Las Vegas, perhaps to go along with a news story in the Las Vegas Gazette? It could have also possibly been taken once they arrived in Santa Fe.
There are many things about this photo which makes me think that it may indeed be authentic! The man on the far left who is supposedly Pat Garrett looks exactly like Garrett in his "known" picture that appears on p.290 of Frederick Nolan's book "The West of Billy the Kid" (I posted this photo below for comparison). He tilts his head the very same way and is wearing the same kind of hat, if not the exact same hat that Garrett is wearing in his "known" picture. Also if you look at the supposed Billy on the far right he is wearing the same style, if not the same small brimmed hat that he wore in the famous tintype photo. His hands also appear to be bound as though they may be in cuffs. Also be sure to notice that the man directly to the left of the supposed Billy is pointing what appears to be a gun at him in a show off type fashion for the photographer. Is this really a photo of Billy? I have no doubts!
Pat F. Garrett
This is an authentic photo of Pat Garrett that has been published numerous times over the years. Compare this photo of Pat Garrett to the supposed Pat Garrett on the far left of the Posse picture. I personally believe the posse photo is authentic!
Compare the close up of the posse photo with the photo that Nick McCarty has on his main page from Paulita Maxwell's album. The similarities are eerie!