Mental issue. Do during this pandemic.

My father has some mental issue around 10 years. But from last 2 years, it is quite more and he is hypertension and angry without any reason. Sometimes he tells to kill people and sometimes he is fine. My mother passed away 2 years back. Also without any reason he scolds family members , also to neighbours. He has a fear that, somebody is stealing from our house. But everytime he will lock his room and key will be with him always. I dont know, which expert to show. As previously, i have shown to one physchologist and as per him, he is perfectly fine. Today my father told one neighbour to kill her and then he will go to jail. This is going out of hand now a days. Please help or suggest me, what to do during this pandemic.