Jimmy Wells did not personally arrest Bob because he was emotionally disturbed on recognizing his old friend. Therefore, he sent a plainclothes officer to arrest Bob to avoid personal pain.
Step 1: Recall the relationship.
In “After Twenty Years”, Jimmy Wells and Bob were close friends who had parted twenty years earlier.
Step 2: Emotional conflict.
When Jimmy recognized Bob as a criminal, he found it difficult to arrest his friend himself due to emotional attachment.
Step 3: Final action.
To perform his duty without personal distress, Jimmy sent another officer to arrest Bob.