What John says ...
Sam's story has two of the ingredients of many successful short stories: a surprise ending, and a baddie who, finally, has to face justice.
Here, the cunning criminal, who makes his money cheating innocent girls, gets tricked himself.
Caught In A Trap is told in the first person - the policewoman tells us what happens to her. This means we experience the story from her point of view, and we get to feel what she is feeling as Chris tries to trick and then rob her.
Usually if an author uses a first person narrator - that's the person who's telling us the story - we also discover a lot about what's going on inside that character's head, what they're thinking about.
In Caught In A Trap, the surprise ending won't work if we know our narrator is a policewoman investigating Chris. But it's hard to believe she never thinks about her duties when she first meets the con man and then plays along with his attempt to cheat her out of her money. Or that she would be shocked at being asked to pay HK$20,000 - surely she would have been informed about his methods beforehand.
One way to solve this problem, and keep the surprise ending, would be to tell the story in the third person. This means we would not be 'inside the head' of any one character, but we'd see everything from the outside. We would still refer to Chris as 'he', but the policewoman would now be 'she', not 'I'.