On Friday, May 12, 2000, the owner of a small grocery store was confronted by a man who demanded money from the cash register. The owner immediately handed $110 to the robber, who took the money and started walking away. Suddenly, and for no apparent reason, the robber turned and fired two shots at the owner and his five-year-old granddaughter, who was standing behind the counter. Both victims died instantly. Two hours later, the police arrested a suspect and changed him with robbery.
Summary of Arguments Presented by the Prosecution
- The robber was seen running into the same apartment house in which the defendant lived.
- $123 was found in the defendant's room
- Traces of ammonia used to clean the floor of the store were found on the defendant's shoes.
- Chemical tests to determine whether a person has gun powder on his hands from firing a gun indicated that there was a slight possibility that the defendant had fired a gun during the same day.
- A clerk who was in the store during the robbery testified that he saw the defendant shoot the two victims.
Summary of Arguments Presented by the Defense
- The defendant testified that he did not commit the crime.
- The defendant testified that the money found in the room was his savings from two months.
- The defendant testified that the ammonia traces on his shoes could have been obtained at a different place because he worked as a delivery man.
- The defendant testified that he had never fired a gun in his life.

Please answer the following questions

What is the independent variable (i. e., what was manipulated)?
What is the dependent variable (i. e., what was measured)?
What is your hypothesis? Why is this your hypothesis? (Hint: Make a prediction about how the independent variable affects the dependent variable.)