Autopsy.
Usually you can find them at the Ministry of justice. They are able to provide you with much more detailed information in regards of a death without a certificate.
on the internet
How to find the cause of death
An autopsy is usually performed where a cause of death is uncertain or unknown (poisonings, for example), or to find out the exact mechanism of death (as in stabbings and gunshot wounds).
He died on October 15 1978, but I couldn't find the cause of his death.
Look up the soical security death indx on the net or order his death certificate from the state where he died
how one day we find out
To find the cause of death.
to find out the cause of death
A pathologist studies dead bodies to find out the cause of death.
You cannot always find the cause of death, but you can type it in
He was a lion tamer.