Unfortunately, he didn't know how to pick a lock, nor could he leave any traces.
So, he could only rely on deduction again.
"Hope I get lucky this time."
Arthur mumbled, beginning to search the area.
If Martin was so careful about locking his door, he probably wouldn't just take the main key with him. He likely left a spare key somewhere near the room door.
Of course, this was just a guess based on normal thinking. It was entirely possible that Martin hadn't hidden a spare key, or he had hidden it somewhere else. Both of these cases could be true if Martin was trying to hide something at a much higher level than a normal person would think, which would make it even more suspicious.
Fortunately, that scenario was unlikely.
Martin didn't know he was a suspect. And his mother wouldn't pay such close attention.
So...
"Found it!"
Arthur let out a sigh of relief, taking a key from the top of the door frame.
The door frame was a wooden part that protruded from the wall, forming a small ledge just big enough to place a flat key on without fear of it being discovered or falling down. Of course, unless someone was over two meters tall and had a horizontal view of that ledge, they wouldn't see it. Looking up from a lower diagonal angle, you wouldn't see a thing, and even from a distance, it would be extremely difficult to spot, as the flat key lay tightly against the ledge, not forming a distinct shape.
Arthur didn't waste too much time, immediately inserting the key and opening the door.
The window was on the wall opposite the door, facing the front of the house. The bed was in a corner of the room, next to the door. The desk was opposite the bed, slightly askew from the window but still getting good sunlight. The bookshelf and wardrobe were on the other side, filling the rest of the room.
All in all, the room was... a normal private room, something any teenager Martin's age would have.
Of course, in terms of details, it was a bit messy. But unless Martin had a specific disorder, anyone's room would have a certain level of disarray. And that was Arthur's guiding principle for finding clues.
To find out what Martin was hiding, or at least to get a general idea of this boy in the shortest amount of time, Arthur used a concept he called the proximity of objects.
From the original concept—that the "room" of the mind projects onto the physical room, allowing Arthur to get a general idea of a person's psyche through physical objects—Arthur advanced to a deeper level.
The human mind always has many parts, many components, and many thoughts at different times. Therefore, most of their physical rooms are the same. However, within that chaos, Arthur could uncover the patterns within those parts. From that, he could deduce that the most orderly parts were the ones closest to the root of their psyche.
This explanation might still be a little hard to understand, so let's use the example of Martin's room.
Compared to his desk, Martin's bed was quite chaotic; the pillow and blanket weren't even folded. Meanwhile, the desk with its books and notebooks, while not perfectly neat, showed that Martin had arranged them by distributing the objects and stacking the books or notebooks so that the larger ones always supported the smaller ones, in a pyramidal shape.
This proved that compared to the bed—a place Martin only used to lie down and sleep—the desk was much "closer" to his psyche. He spent time there and paid attention to that spot, so he wanted to arrange it. Subconsciously, he made it "better" and "more "aesthetically pleasing."
The same went for the bookshelf, but the bookshelf required a slightly more careful distinction. Because a bookshelf itself represents a kind of order.
Of course, before checking the bookshelf, Arthur glanced under the bed and in the wardrobe. Although there were a few things in there, nothing was suspicious. The "proximity" of these two places was even less than the desk.
As for the bookshelf, Arthur quickly scanned it.
Martin's bookshelf was very jumbled, as if things were just taken out and put back into any empty spot without purpose, a mix of magazines, comics, paper manuscripts of something, etc. Sometimes, the books were even shoved in with their spines facing inward, or not pushed all the way back to touch the back of the shelf.
It could be said that the "proximity" of the bookshelf was still lower than the desk.
Until Arthur's eyes landed on a niche in the center of the bookshelf.
Compared to the jumbled books around it, the books in this niche were strangely neat and cohesive. They were uniform in color, arrangement, and layout.
Continuing to apply the concept of the proximity of objects, Arthur concluded that compared to the other parts of the bookshelf, the books neatly and uniformly arranged in this niche were the things closest to Martin's psyche.
Just as Arthur was about to see what these books were, the phone in his pocket suddenly rang.
Arthur didn't answer but just looked at the caller.
It was Sarah.
Before, he had told Sarah that if there was any problem or if he had been gone for too long, she could call him. Arthur wouldn't answer, but would take it as a signal.
"That's enough for now."
He let out a sigh, quickly using his phone to take a few pictures from different angles of the room's layout, especially the bookshelf and those books, so he could examine them later. After he was done, Arthur gently closed the room door, locked it, and put the key back in its original place. Then, he went downstairs.