6 Answers

If you really feel there is some "foul play" involved, do contact the police agency that responded to your father's accident and ask them for a report.  You may have to pay $10 or so, but that is a starting place.  If an autopsy was performed, you can also request a copy of that. 
If there was a good motive for your step-mother (I'm assuming she is not your bio-mom) to have your father pass, and any suspicion about his death, an investigation can be conducted. 

How to live with his death if you can't get "satisfaction"?  Faith.  Contact a "help" line and ask for a counseling referral. You may need to have someone who will listen to your concerns and help you work through the grief process.   

"What to do if you suspect foul play involved with death of a loved one"....I ran this through the bing conduit and the first four links here may be of interest for you to read>>>http://www.bing.com/search?q=What%20to%20do%20if%20you%20suspect%20foul%20play%20involved%20with%20death%20of%20a%20loved%20one&pc=conduit&ptag=AA86C9977A80442CA91F&form=CONOMX&conlogo=CT3210127&ShowAppsUI=1

It`s terrible for you to lose your Father(Sympathies to you)!...I can only say I`d not be able to rest until I had a full investigation...It does sound suspicious...you need to know the truth...I feel very sorry for you,...I wish you well...please get advice from police or  a helpline...I don`t think many people could/shuld try and cope with this alone!

dont trust her

It is your choice to be happy or right. Choose happiness, it is so much easier to live with.

my father had a pillow placed under his head and he died. I cant understand why his wife needed to put the pillow there if the death certificate shows he died three hours before she said? am I the only one that if confused because I have to figure this out