Two interesting things:
Her killer came at her from behind, striking her in the back of the head with a wooden mallet. Time cards flew out of Freeman's hand like confetti, scattering across the floor. Her attacker struck her repeatedly in the face, then cut her throat. A guard making a routine sweep of the building found her body several hours later.
And this...
I am curious if her killer planned her murder a few hours earlier prior to the actual murder. A couple of the murder weapons weren't found but the wooden mallet was found. I find that strange. I just find this whole case strange.
I do think it was planned but not planned. Planned as in fantasy then leaping towards enacting. It's a very disorganized method of killing to leave the body and not clean up. Organized killers always take away all the evidence they can, including the body.
Doesn't feel like the first time they did this to someone. But does feel like an escalation because of how intense and violent the murder was. No one cuts the throat and bludgeons the face like that without hatred towards the individual or women as a whole. Something tells me, the individual has been studying her schedule for weeks or months, as well as security, and then finally went in to do the deed when the least amount of security and staff was around. Some of the hardest cold cases to crack are people who know the schedule of others and can easily slip through the cracks by everyone because they know when to strike.
Now since no SA/rape as it's reported, that means it wasn't sexual homicide. However, if they kept her clothing, they can figure this out now by testing for semen residue to see if sexual homicide either when she was alive or dead (necrophilia) took place. They could also look for if they kept the clothing, any hair from the purp was left on it by accident since humans shed upward of 50-100 strands of hair a day. So maybe there is hope regarding this. So till this is confirmed, if they kept anything from her for her case, we gotta assume at this point it wasn't sexual homicide motivated.
Anyway...
My guess? Either a repairman, janitor or someone newer in town passing through in the county or neighboring states, who was linked to other similar methods of killing. The best bet is to find out if anyone else in the 10yrs before and 10yrs after also was beaten in the face heavily and throat slashed, that had similar builds, age, and hair/eyes to see if anyone else is linked.
Heck, double-check the visitor logs to staff logs for patterns of anyone new who was always on the same shifts as her.
I'd look at reports if any available to the public that the police have released, looking up her home routes from work, where she hung out the most on her days off, and so on.
And I mentioned repairman because...
I looked on a weather site and the weather in Clifton, NJ that day had a "mean temperature" of 70 degrees on August 31st, 1968 so it wasn't really that hot on average. The maximum temperature was 79 degrees though that day. Where I am getting at is I am referring to my first post on this thread that the A/C may not have been working or working properly in the Building that Joan usually worked in.
If in fact the A/C was broken and if that library was warm, all she needed to do was contact a repair person to come to the location and fix it if no one on campus/staff was qualified to repair it.