Final answer:
Lencho protracted his visit, examined the letter, and left after discovering it had been tampered with.
Step-by-step explanation:
After opening the letter, Lencho took several actions. First, he protracted his visit to maintain a distraction while secretly examining the letter. He memorized its appearance and arrangement in the rack, and noticed that the edges of the paper were chafed, indicating the letter had been turned inside out and resealed. Lencho then bid the Minister good morning and left.