My suspicions

Last week, I found out that my dad and his long time gf died last week in their home. His death was unexpected to me. My father was ill with diabetes and kidney issues, I always thought that he'd pass away from old age or his illnesses. We didn't expect him to go so soon at 57 years old. we last spoke on Thursday the 10th and I got the phone call from the coroner last week on Wednesday, prior to getting the worst phone call of my life. he wasn't answering my texts or phone calls I started to worry. I spoke to the gf's mom who said that she had spoken to her on Friday the 11th but when I'd call my dad on Friday he wasn't picking up and my calls would get forwarded and he was missing his dialysis appointments. I have a suspicion that she murdered my father, so far all I know that is it looked like an overdose of a white substance but what I'm thinking is that she poisoned my father as he trusted her with his medications. I think she killed my dad then kept his body for two days then proceeded to kill herself due to panic. My dad and her had a welfare check done because he was missing his dialysis appointments so, I'm sure that she killed him. I went this Saturday to pick up his personal belongings her family ransacked the entire place and went through his stuff they packed all of the shitty stuff behind my back but kept all his valuables such as his guns, jewelry, cash, devices, documents even the keys to his truck etc. These people ganged up on me and one physically assaulted me they blamed my father for her death, saying that he induced her into drugs, but she was no child she was a 300 lbs elephant who had vices and was almost hitting 40. She was no saint, they then started blaming me and bad mouthing my father. I am already starting a case to press charges on them for theft and battery. Her mother thought that she would get ownership of my father's body she was making funeral arrangements to have both him and her fat druggie daughter buried together and she set up a go fund me asking for donations for the both of them while I'm having my father cremated. I'm pissed off but I will get that lady. The cops in the county I live in suck idk where to seek legal assistance for my suspicions about his death. The coroner will only state that it was an overdose but I'm certain that he was murdered by that fat cowardly bitch. My siblings and I are extremely pissed off over all of this. The gf took his surname they were never married but she claimed that they were. My parents only separated never divorced so, my mom is actually legal next to kin and so are we not his gf or her stupid family. I will have to avenge my father.