Also, in the beginning of the book, we learn that Bigger's family is very poor. They live in terrible living conditions mostly due to segregation and racism, but, Bigger for a long time had turned down so many jobs. He was the second oldest person in his family, his mother being the oldest. He should've taken the responsibility to get a job and try to provide more for his family. This had given me a bad impression of Bigger since the beginning.
Bigger had let his feelings bottle up so much for so long, that all the emotions finally exploded and caused these horrible chain of events. I agree that he should've gone to prison, but I don't agree with giving him the death penalty.