John Cook

Author John Cook discusses of a new report that says the vast majority of studies say humans play a role.

A Colorado man who had just been released from jail on domestic violence charges shot and killed three people Tuesday, including his ex-girlfriend, who was on the phone with a 911 dispatcher when she was killed, authorities said. The gunman then shot and killed himself, Weld County Sheriff John Cook said. The victims included the ex-girlfriend's sister and the sister's husband. All were found dead in a home in unincorporated Weld County outside Longmont, about 35 miles north of Denver.