Verified answer

They can never know for sure.

I don't think they can always tell with known drug addicts or heavy drug users, they could have started out to get high and just miscalculated or took the wrong combination. On the other hand if they left a suicide note, or were known to be suicidal it's pretty certain it was suicide.

you never know, scientists cut open their stomach and count the pills and determine if it was suicide or not.

Usualy an accident overdoes means the doctor told them to take that amount.

i TRIED THAT AND THEY GOT ME TO THE HOSPITAL MD PUMPED ME OUT. I DID AN OVERKILL.

JUST GOT BACK FROM A MENTAL WARD.