Sleuthing friends and family and discussing their personal information on the thread is outside of TOS except information reported by LE or MSM. The exception seems to be the people in the VI's timeline, but I do not know why since they were not named by LE.
However, we are usually free to discuss theories that do not name (or specifically focus on) a particular individual. The focus is on not bringing innocent people into a thread. We can still develop a picture of a suspect or suspects based on what we know about the victim.
For example, I think it is fine if we discuss if we think Car 3 was a known or unknown individual. We would not be "naming and shaming", but rather discussing what may have happened.