There is a decrease, of course there will be but there are still some out there and if you put them in jail and ruin their life they may feel bad and never again, in addition you aren't killing people. As said by Vijai P. Sharma, Ph.D "Words Can Hurt More Than Sticks And Stones" Sticks and stones can create death and if you hurt them from the inside it will create more damage here is a site proving it http://www.huffingtonpost.
Then you become the murderer. Even the creator of the lethal injection said it was bad.
The man who invented the lethal injection method of execution told The Guardian that miscarriages of justice and botched executions have changed his mind about the death penalty.
This is coming from a news site
Sola, Katie. "Inventor Of Lethal Injection: 'I Am Ambivalent About The Death Penalty'"
The Huffington Post. TheHuffingtonPost.com, n.d. Web. 28 May 2015.