What happened to David, by the way?

You aim at the doorknob to fire another shot at it. As you do so, you hear someone enter the yard behind you from the east. You pull the trigger, and a loud gunshot rings out as the doorknob takes further damage. You cock the hammer and the cylinder turns to line up the next cartridge. Someone behind you yells "Control plus Z! Control plus Z!"

You begin walking south, opening the door ahead of you as you enter. You see that you're inside the garage, and a number of florescent lights illuminate the area. Looking around, there are quite a few items cluttered around, and a few metal shelving units. The items include a blue tarp, a coiled nylon rope, two black flashlights, a few cans of paint, a few paintbrushes, a paint roller, a paint roller pan, a few dirty rags, a red gasoline canister, a bag of charcoal, a roll of duct tape, an assortment of firework supplies, and a roll of fuse.

DavidJCobb is standing here with a zoned out expression on his face. He has what appears to be a large cardboard box attached to his back with rope straps around his arms. He is also wielding a knife that's covered in blood, and the front of his shirt is drenched in blood as well.

You take your lasso and throw it around him, pulling him toward you, and he offers no resistance. You pull out your personal knife and reach around in front of him to press it hard against his throat, then make a fast pulling motion. The blade easily slices through his flesh, and blood gushes out of the wound as he drops to the floor, motionless. A red pool quickly forms beneath him as the blood rushes from his gaping throat. The lasso is still tied around him.

As he hits the floor, the items from his backpack scatter across the floor, spread out in such a way that would require a separate action to acquire each item individually. The items are a coil of nylon rope, a sharp piece of wood, a barbecue lighter, a key, a garage door opener, a crowbar, and a butane torch. He also drops a bloody knife beside him which is identical to the one you slit his throat with.

You note that your hands are now thoroughly full, holding the end of the rope, the meat cleaver, the gun, and your personal knife at the same time.

Still holding the book, you pick up the two full whiskey bottles and wield one in each hand. You use the fingers you have free to flip back another page in the journal, to an entry dated seven days ago.

"My plans have already been set into motion! Today I was talking to someone and casually brought up the topic of them coming here for the weekend. At first they declined, saying they would be busy on Saturday, but then offered to stay for a few hours the night before. This has given me a great idea! If anyone declines to stay the entire weekend, then I'll ask if they can come for a little while on Friday instead. This will allow me to invite many more people than I originally thought possible.

My new cell phone is also working well, and greatly facilitated the exchange of information with him. All I have to do is add anyone who agrees to come to my contacts list, and I'll be able to call them all quite easily when it's time to arrange their transportation. Letters and face-to-face arrangements are much more personal than a telephone, but if I'm going to be making some friends then I suppose I'll need a way to communicate efficiently with them. It wasn't that long ago I would have never considered owning a cell phone, now I can't even imagine not having it with me."

You flip back another page, to read an entry dated eight days ago.

"I'm starting a new chapter of my life today, and thus a new journal to commemorate it. I refuse to live a lonely existence any longer, and have come up with a way to solve the problem: I will begin inviting people to spend next weekend here! I can only invite three people, though I'll hopefully make friends with at least one of them. I need to start making plans and deciding who I will be asking."

Another entry is below it, with the same date.

"I had a remarkable idea earlier! I went into town and visited a furniture supplier, who is bringing out a number of beds, nightstands, and similar things for the guest bedrooms. Now I will be able to invite six people, two to each room. Some may be uncomfortable with that, but I'm sure I can find six to fill the rooms, that's less than one person per day! Tomorrow morning I'm going to shop for a cell phone, something I'm not happy about but it is an unfortunate necessity. Although business arrangements are easy enough to make without a phone, I'm afraid that personal relationships are not. I'm sure I can get used to it though."

You note that this is the first page of the journal.

Clarification: I only killed 4 people, including owner.

The owner's cell phone was in his back pocket the whole time

By the way, if you look at those entries in order, it should be clear which one refers to the killer.

What was the evidence piece you said the killer was able to physically remove?

Quote from Tuxedo-Templar

What was the evidence piece you said the killer was able to physically remove?

The bloody clothes in the room of EzTerix and Zilean were from the killer. LoTu)S was drenched in blood when he committed the murder, and ran up to his room to change. He heard the scream as he was finishing up, and left his room, throwing the blood-soaked clothes into their room when he walked by.

However, unknown to him was that in his haste to remove his shirt, he had broken one of the bloody buttons off while he was disrobing. The button fell into the pocket of the pants he had just finished changing into.

The reason he could only find this evidence with a physical action is because its presence was unknown to him. When he said "Recall what items I have in my pockets," it wasn't on the list. Physically checking the pocket was the only way to discover it.

Not like people would check my pockets anyways.

You mentioned other empirical evidences pieces. What were they?