Yeah besides the fact it was a stabbing death and a loose time proximity Im not real convinced there was a link with Mineo's murder.
Of course considering some of the high powered Hollywood players she partied with and the Cocaine saturated millieu Christa inhabited I seem to remember their were rumours that she kept some sort of diary ala' Marilyn Monroe that might have provided a motive but who knows if that was true.
Christa was also reportedly quite bisexual and there was some speculation that her assailant may not have been a man ,the manner in which she was killed,up close stabbing, often suggests a very personal motive for a killer.
Given the time and the place and the police attitude of 'Too bad: live freaky die freaky' not to mention the Entertainment Biz influence in a very 'company' town im not surprised the investigation didnt get too far.
But at the end of the day someone got away with a very brutal murder it would be nice if there was some kind of resolution or answer but its probably unlikely barring a death bed confession.
Im sure there are probably quite a few folks who know what happened though.