Legal help needed on my father's suicide

Hi experts, I need legal help in my father suicide case. I'm from Andhra Pradesh and my father Satyanarayana Reddy committed suicide due to harassment of a group of a people in the village. He wrote a suicide note saying 6 people harassed him because of political motivates. he committed suicide on 27th July, I've complained about it on the same day the police station and informed them about the suicide note. Police registered the case with crpc 174 section. It is 25 days till date and the people who harassed my father are free on the roads and passing comments saying they have political influence and nothing can happen to them. when I talked to police they say they are waiting for the Forensic Science Lab report on suicide note examination and they will the change the section to IPC 306 only when they get the result correctly. My father consumed pesticide and they say they are waiting for post mortem report too for taking any action on them. we have handed over the receipt of the purchase of pesticide that we found in the house to the police. They are asking for few more signatures of my father every other week. The accused are bullying us with political motivations and roaming free on the roads. As an educated person I couldn't digest that political power wins over the truth. As I'm not aware of law posting here for your valuable suggestions and help. I've many a questions running on my mind. 1. Won't they arrest the people mentioned in the suicide note though my mother and I clearly they harassed my father?. 2. The accused clearly say they got backing from some one high in the state govt and I heard comments saying they can make forensic reports false using money/ political powers. 3. Police are not really active in perceiving anything in this case, every time I call they say waiting for the Forensic report to come. Please suggest me how can I proceed with the situation. Sorry if my question is big. I would be very grateful if you can help me get justice.