Having been subjected to the displeasure of a high profile person in another business setting many years ago, I can well imagine the Captain, if his allegations are true, presents with what is allegedly termed "a major depressive disorder". I would suggest it is similar to PTSD but I am not a doctor. Anyone who experiences the anger of one of these creatures would.
The way the perpetrator inflicts pain on their targets is via whispering campaigns, character assassination, social bullying, gaslighting, deliberate ostracism, allegations of poor performance, aggressive supervision, downgrading and other forms of professional and social exclusion that, metaphorically speaking, leave no blood or fingerprints.
Each of the attacks by themselves are portrayed as either reasonable corporate actions, accidents, misunderstandings or innocent mistakes so that the target appears to be paranoid - as any good legal team will allege.
It is only when the totality is experienced that the intention is obvious to the victim. Co-workers either are complicit or naively believe that no one would do such a monstrous thing (they are wrong) and therefore the victim is exaggerating.
Such an experience will leave permanent psychological scars. I don't think I need to explain how its done. Good luck to the Captain in proving it, I don't like his chances.