The Dallas Cowboys' last second loss to the Green Bay Packers last weekend was devastating for Cowboys fans for sure, but it should never reach a point where someone gets killed because of it.

Las Vegas Metro police are reporting that 46-year old Robert Boyer murdered his 40-year old brother Justin Boyer following a heated altercation after a night of drinking and watching the Cowboys game.

Friends who were present say an argument broke out between the two men and a roommate had to physically separate them as things escalated. Justin allegedly attacked Robert again soon after at which point Robert, who says he feared for his life, pulled out a knife and fatally stabbed his younger brother.

Neighbors, Robert Lewis and Patricia Lewis, said they found Justin at their front door with multiple stab wounds.

"He just asked for help. He was moaning he needed help,” Patricia said to NBC 3 News Las Vegas. “He was obviously intoxicated. He was just begging for help."

"I’m passionate. I’m an Eagles fan and I’m passionate about my Eagles," Robert Lewis said. "[B]ut to get to that level over a ballgame is just crazy. Unreal. Unbelievable."

Justin ultimately died at UMC hospital. Friends say that he suffered from mental illness and that the Cowboys loss triggered his anger- officers believe Robert's claim that he acted in self defense.