That “no good son of a bitch” did make a couple dozen phone calls from a pay phone near the scene. It would be interesting to know to whom those calls were placed, and what was said.
One theory that I found interesting. Kennedy wasn’t driving. Recall that a cop on pateol had driven by the parked car. The story goes, he got spooked and unassed the area. Kopechne then tried to drive the car back to the party, but she was unfamiliar with the roads and ran off into the water.
He was probably calling dad, lawyers and other Kennedy family fixers.
That's not a theory, that would have been his defense had it gone to trial.