For Li Wei, an investigation did not begin with "What exactly was unusual about this?"
First, he needed to establish "Did this actually happen?"
Police in the real world often encountered this sort of thing too. Sometimes, during questioning, a criminal would suddenly confess to other cases in hopes of receiving a lighter sentence. The account sounded convincing, complete with times, places, and people, leaving the police stunned and convinced such a case existed. But when they sent someone to investigate, nothing of the sort had happened!
So when investigating a case, whatever the other party said, one should not begin by assuming the incident had happened. First, one had to consider whether the incident itself was real.
The story Isaac had told, for instance, contained an inexplicable contradiction.
Why had the postman left his mailbag behind instead of taking it with him?
It was like a student going to school and telling the teacher that someone had stolen his summer homework on the bus. The teacher would ask, "Why did they steal yours specifically, and not anyone else's?"
Unless the thief was subsequently caught and the police delivered the summer homework to the school, the student could not prove his innocence.
Of course, if there was not a single word written in it, that was another matter altogether.
The same applied here. Isaac had sounded aggrieved and utterly convinced of his own innocence, as though protesting that no one should sully his good name.
But Li Wei still could not be certain he was not lying.
Not unless there was evidence proving that Isaac's account was true.
The postman having visited could not prove it. Someone having seen Isaac hand the postman something could only establish part of it, unless a third party could recount the circumstances in detail-and