This group of pictures really haunted me at first. However I now think this kid was not a victim, that he knows about the Alcala case, and he has probably seen his own photo online but prefers not to make himself known. I think he was a smart, savvy kid from a secure home, with a comfortably-off family and good peer group status, that he lived not far from RA, and that RA knew or had at least met his parents.
I realise this is a bold claim to base on a few scant photos but I think the evidence is there. The fact that RA was the photographer might at first suggest an awkward, vulnerable adolescent stopped on the street, but this does not look like a runaway or a boy from a poor family. The jeans and shirt have some wear but they fit him well and look good quality. They appear clean, so does he, and his hair is not cut just anyhow but is well styled for the era. He has a cool, expensive bike. How he got the broken teeth - which he's trying not to show - I have no idea, but he isn't from some breadline family. He doesn't look more than 15 but he's got clear lovebites on his neck, which at least one of his parents must have spotted. Since they evidently took good care of him, it is doubtful they let him slide into the clutches of a male abuser, and since being openly gay in that time and at his age was extremely unlikely, he must have got them from his girlfriend. Inept and mentally-challenged teenage boys don't tend to have those.
I see no sign of fear or apprehension. I don't think the awkward pose is because he's gauche, naive, whatever. He probably just wasn't interested in being photographed, maybe he was self-conscious about the missing teeth, but it was a case of ok, go on then and take your photos if you really must. He's not particularly enjoying the situation but he's not that bothered by it either.
The bike is on grass, a few feet from a house and no sign of any tarmac. Either the house is right on the road or RA has got him him to carry his bike onto someone's front garden. Assuming these to be unlikely, he is either in RA's own garden, someone else's, or his own. If RA was living with his mother and intended foul play, he was unlikely to risk luring the boy there in broad daylight, and anyway this particular boy is probably too streetwise to fall for that . A stranger's house seems even less likely.
I infer from all this that the boy was not a random encounter but was known to RA through normal social channels. He's the son of friends, relatives or someone RA had dealings with, and RA has photographed him at his own home. The boy would have preferred not, but RA was a guest and it was impolite to refuse. He will be almost certainly aware of the Alcala case, as even if he didn't know who RA was, his parents must have done and they will have told him. People who've met a serial killer will normally take an interest in the case and follow its progress. If he's done that, he must know about the photos, but he hasn't come forward so he doesn't want to be associated with the case or be questioned about it. Maybe he just doesn't want to get involved. Maybe he has even seen this thread.
Can anyone provide a high res picture of the bike? The writing on the frame might be decipherable. A first name, middle initial and the beginning of a last name look fairly clear already, unless this is the title of a bike edition. Unfortunately there doesn't seem to be much online about the history of the Omega cycle company.
I very much hope that I'm right and that this kid (= this 50ish year old man) is alive and well. It would be great to have confirmation of that but we'll probably never know.