The Investigator in charge of the Michael Vick case writes that Vick “thought it was funny to watch the dogs… injure or kill the other dogs.” He also writes that Vick and his associates killed dogs in many ways:

By hanging: “by placing a nylon cord over a 2 x 4 that was nailed to two trees located next to the big shed.”

By drowning: “by putting the dogs’ heads in a 5 gallon bucket of water.”

By beating: “by slamming [dogs] to the ground several times … breaking the dog’s back or neck.”

By shooting: “by shooting the animal with a .22 caliber handgun.”

By electrocution. According to one of the people Vick paid “to live on the property, take care of the dogs, and arrange dog fights,” “He admitted killing numerous dogs after ‘testing’ and after fights by shooting and electrocuting the dogs and then burying them on the… property.”

http://www.examiner.com/animal-shelters-in-san-francisco/no-sympathy-for-michael-vick