The case of Carlos DeLuna is one of the more simple cases to comprehend. I'll try to be quick.
Corpus Christi, Texas, February 1983. George Aguirre pulls into a gas station and notices a man outside with a knife. The man asks Aguirre for a ride. Aguirre declines. The man goes to the side of the building. Aguirre goes inside and warns the clerk, Wanda Lopez, about the man with the knife. Aguirre leaves.
Lopez calls 911 and tells them about the man with the knife. They say they can't do anything, that she should call back if he comes inside. The man with the knife comes inside. Wanda Lopez calls 911 again and tells them that the man with the knife has come inside. She begins to scream. The 911 operator records the last moments of Wanda's life.