Someone told me that there's a deleted scene on the Godfather special features DVD, in which Don Corleone asks for Luca Brasi after hearing that Woltz isn't complying with the request to star Johhny Fontane in the new war movie. I believe Luca Brasi physically didn't put the horse head in the head. I belive Luca arranaged the head getting cut off and had someone who worked for woltz bribed and they did the job, Brasi was in charge of hiring the right men for the job this is my thought on who actually put the head in the blanket, had to be an inside job because a stranger would have been caught and kicked out of the house.