Cox said he dove behind the counter and called 911
while customers and his manager ran from the coffee shop. At least twice during the call, Cox said, the dispatcher asked him to look around the shop so he could give her more information.
Each time he looked up, Cox said, Zhu was on top of Yang, who was on the floor. Zhu stared at Yang's face as he cut through her neck, Cox said.
"It wasn't really an angry face at all," Cox said. "It was just a really blank, determined look."
By the time police arrived, Zhu was holding the woman's head in his hand, an officer testified.
"I saw a body lying and I saw a gentleman walking toward me with a head in his hand," testified Nicole Irvine of the Virginia Tech Police Department.
Irvine said he dropped the head when she ordered him to put his hands in the air.
Witnesses have told police that Zhu and Yang were drinking coffee together and had not been arguing before the attack.
Irvine said she found a kitchen knife lying on a table in the cafe and Zhu told her he had knives and a hammer in his backpack