Yes, I believe that Sirhan is still alive and imprisoned. I recall that he was recently denied again on an application for parole.

No, I am not aware of his ever having been mentioned as possibly having been involved in the JFK assassination, and I think it highly unlikely that he was since he was only nineteen years old at the time.

However, there has been some speculation about the RFK murder and Sirhan's role in it which, for some reason, has managed to stay under the radar for the more than 37 years since the event itself.

I would guess that there are very few people who are even aware of the fact that the case against Sirhan is anything but open and shut, and that theories abound involving misconduct by the FBI and/or the LAPD, and the suppression, outright disappearance, concealment, and/or tainting of evidence.

At least that's what I remember from the two books I read on the subject several years ago, both paperbacks:

The Robert F. Kennedy Assassination: New Revelations On The Conspiracy and Cover-Up, by Philip H. Melanson (1991; S.P.I. Books, New York,); and

Shadow Play: The Untold Story Of The Robert F. Kennedy Assassination, by William Klaber abd Philip H. Melanson (1997; St. Martin's Paperbacks, New York).

(I guess this Melanson must be one of the experts in the field).

I don't remember much more in the way of detail other than the above (and I needed to read the books back covers and stuff to recall even that much ), but I do recall that there was also some business about a missing door frame from the area in which RFK was shot, in which the number of bullet holes or something would have provided proof that there was more than one gunman, and some other proof that there were eleven shots fired in total and Sirhan's gun only held eight rounds.

I also just did a quick googling of "Sirhan Sirhan", and there's a ton of stuff out there, altho I didn't look at any of it.

Maybe you'd like to, Goombah, and report back.

Edit: My aologies for the redundancy with MMTH's post. I started writing mine, and then stopped in the middle to look for the two books, which I had trouble finding.