It's not that you don't need a ladder. On the contrary, you need a ladder. However, because of the weight problem, the murderer can't use the wooden ladder near the scene (because the wooden ladder has limited bearing capacity), so he must use the iron ladder, which can prove that the murderer is a heavy island.

Ladders are used because, as mentioned earlier, a smart athlete with a height of 180cm can't reach the top of the bookshelf, let alone others, so to build a fake bookshelf, a ladder must be used.

It's not enough to have a corpse, because someone will check it and find that this bookcase is much shorter than the others. Wouldn't it be weird? Therefore, it is prudent to build it as high as ordinary bookshelves. I rummaged through it several times, but I didn't see the sentence "There are only three books missing from the bottom shelf behind the body". On the contrary, in the scene where I went to the library with Shima and Zhi Zhi, I said to Shima himself, "If the murderer built a bookshelf here, books could not be arranged on it without a ladder." The instructions must be "as high as ordinary bookshelves."

Hehe ~ ~ ~ Is there a problem?