Context: There is a man who is telling a story about himself. You can call him Bi. Bi was a suspect of assault and was sent to the prison. And one of the lines in his dialogue is "父は服役してる間に自分で死んだ｡"
I tried to translate this sentence with the help of a friend, and we went for this sentence: "My father died on his own while I was in prison."
But I'm unsure as to whether the 自分 here means Bi's father committed suicide? Is that the case, or did Bi's father die alone when Bi was in prison?
Thank you in advance.