Crime scene: 162 mystery solving puzzles to find out who the murderer is

Chapter 121 The Dog Killed Its Owner

At noon on Monday, accountant Shen was bitten to death by his dog while talking on the phone with others.Some time ago, Shen went on a trip for a month and couldn't keep the dog himself, so he entrusted his friend Shi to do it for him.

The police officer inspected the scene and listened to Shi's report: He brought the dog back to Shen's home on Monday morning, and Shen was in the laboratory of the research institute when Shen was killed by the dog.The research institute is 5 kilometers away from Shen’s home. Even if Shi deliberately trained the dog to bite people during Shen’s absence for a month, it was impossible for him to order the dog to kill Shen from 5 kilometers away. .

The sheriff cleanly affirmed that the real murderer was Shi.It was he who set the trap and let the dog kill Shen.

How did the sheriff judge?
[Answer] Shi trained the dog to bite when the phone rang, and then called Shen on Monday to give the dog the command to bite.

(End of this chapter)