Agree it is a big deal to be on probation and usually comes with loss of privileges.Or maybe one of the victims was the whistleblower that got the sororities put on official suspension.
My daughter lives in a sorority house and getting put on probation or kicked off campus is a BIG DEAL. If one of the victims was involved in that, I could see the murders being revenge.
If their sororities were on probation for that semester, it could be the girls held sorority functions or just more gatherings in general at their house since having any type of alcohol or official function in their sorority house would absolutely be prohibited if on probation.
They likely lost the ability to have “official” parties with frats as well, so anything like that would have to take place either informally at the frat, a bar, or informally at the girl’s (or other sorority members) house.
Just providing some background on what being on probation would likely mean (source: I was in a sorority at a large university)