Thanks for your question.
your friend have paranoid schizophrenia
and you probably know in this type people are suspicious among neighbour,relatives also on family member only this things can explain his all symptoms.
Now about the medication-to work or don't work that depend weather adequate dose for adequate time is applied or not or is there any combination of antipsychotics.I hope this all are done according to rule but he didn't response.this is called TREATMENT RESISTANT SCHIZOPHRENIA
He need urgent hospitalization in a mental hospital to reduce physical, economical,familial loss he will do.Then consult a psychiatrist
and follow his advise.in this case we psychiatrist divided into two .some prefer clozapine
drugs and some prefer electroconvulsive therapy
.booth are excellent for controlling violence.
Dr sourav Ganguly