Bobby Bigelow was an average sixth grader. That is, except for the fact that he had the mind of Sherlock Holmes himself. One day, while walking around the block, he noticed two of the students at school arguing over something.

The two boys were Jeremy and Jacob. Jeremy was accusing Jacob of killing his pet cockroach! As Bobby looked at the shiny back of the creature, Jacob explained his story.

"Jeremy let me take care of his cockroach for the day," began Jacob, "I kept it with me the whole day. About half an hour ago, I noticed that the cockroach had not moved for a long time. When I found that it didn't move when I tapped the cage, I called Jeremy. I left the cockroach exactly as it was, and here we are. Jeremy accusing me of killing his cockroach."

After a few moments, Bobby concluded that Jacob had indeed killed the cockroach.

Why was he so sure?