This is all pretty hard, compiling accurate numbers just from the news and the SFPD website (which is almost useless most of the time), so here's my take on the murder total so far this year:
Right now, it looks like it's at least 81, which is what the Chronicle is counting. The Chronicle claims the shooting on O'Farrell is an OD victim, though that seems strange, seeing as many people report hearing a gunshot right before the man died...
(I'm putting this one in the list of unverified murders and suspicious deaths, seeing as there are so many conflicting accounts of what happened, the newest being that it was a suicide, either from jumping from the roof, or a self-inflicted gunshot. So my count is going back down to 81.)
If the double murder last week WAS a murder-suicide, than take one murder off the list. There's no official word on that though, so I'm leaving it as it was initially reported: a double-homicide.
You can also include a couple murders that were reported by witnesses and not the news, as well as some murders that were initially reported as suspicious by the papers, but which may have later been considered murder, such as the man strangled in the Haight early in the year, which in news was regarded alternately as both suspicious, and a murder...it can be confusing.
So, the total COULD be anywhere from at the very least 80 to *possibly* even 88 (or even 90, if the 2 hit-and-run victims a couple weeks ago are included as murders, though I'm pretty sure they're manslaughter). The news and the SFPD website are so inconsistent with their reporting (and when they DO report, they sometimes don't include all the facts) that it's hard to tell for sure.