Bakugo is at the crime scene, eating a relatively bad sandwich he got on the way there (how can a sandwich be bad, he doesn't understand). 

Kirishima stands in front of the door and looks up from his phone. "Oh, hey man! Don't worry, I haven't touched anything or even looked around. I was waiting for you." 

Kirishima looks at his sandwich and makes an expression before masking it. "Ah, dude, you sure you don't want to get lunch…?" 

Bakugo was starting to reconsider his offer to be honest, but he'll think about it later. 

"I'll… consider, later", he replies. He snaps on his gloves and makes sure he has the correct attire on before opening the door into the apartment. 

It was relatively plain. It has a simple design, nothing too complicated and it was considerably modern (for such a cheap apartment). Nothing seemed to be touched or out of place, the entire place is clean and spotless. 

They enter the victim’s room and Kirishima starts looking around. Bakugo stands near the door, staring at the bed where the victim's body was found.  

A gun on the floor…

The woman sprawled on the bed, fresh blood sliding down her forehead before staining the pillow. The stain starts to expand as more blood reaches the fabric...

There was no back splatter, hell, he's pretty sure the bullet is still lodged in her skull. Clearly, she had been shot at a close distance.

He stares at the pillow case, there were tiny droplets of blood it, other than the huge blood stain. There was also a evidence identification marker with a big 1 right next to the pillow on the night stand.

He visualises the crime scene when he first checked it out, filtering everybody out of it except himself. Everything was clean, nobody was in it other than the victim. There was a big blood stain on the pillow case, tiny speckles too. The bullet clearly didn't pierce through cleanly and is still lodged in her skull.

The neighbor was a deep sleeper, if not she would've been woken up by the gun shot, but then what about the others?

The thickness of the wall, he has to think about that too. He's pretty sure the wall isn't THAT thick to completely block out the sound of a bullet being fired from a gun.

Everyone keeps saying it was a suicide… it couldn't be, he doesn't think it's something this easy… 

Suicide… 

Kirishima speaks up, holding onto a piece of tape. "There's no break-in, at least not from the window…" 

Bakugo nods, walking around the apartment with careful and slow movements.

Kirishima watches before speaking up again. "You said the gun was on the floor right. Were there any fingerprints on it? Can you please paint a picture of when you stepped into this room for the first time?"

Bakugo thinks hard, trying to visualize the gun he found on the floor. Yes, there were fingerprints, he checked, they belonged to Suzuki.

Kirishima watches as Bakugo closes his eyes, eyebrows scrunching in concentration.  

He listens carefully as Bakugo describes everything, from the apartment to the body. He even tells him his thoughts about the wall thickness, the wound, why didn't the neighbours wake up from the sound of the gun firing. Bakugo bites his bottom lip as he snaps his finger next to his ear, trying to trigger his memory.

"There was... Dirt... On the gun too...", he says.

Dirt, Kirishima thinks. He turns in a circle slowly, not moving from his spot. The house is spotless, clean. The victim they were dealing with was a clean freak, the neighbor said so. Which meant, she would be clean too, constantly. 

"Try thinking about the body", Kirishima says calmly. 

Little details. His teacher always said to notice little details about everything. Sure, doing it too much may make you lose your mind, but if you know where and when to notice, it's bloody useful. 

Her fingernails were slightly chipped, a little dirt underneath them. Her fingers are slightly red too, and there were little specks of dry blood left, very little specks. 

She could've been out, or, she could've been clawing at something. 

Suffocation has the highest probability right now.  

But then, she was found dead, sprawled on the bed. So perhaps, suffocated by the pillow? 

"Open your eyes."

Bakugo opens his eyes and stares at Kirishima who's staring at the stained pillow case.

"Hear me out. Based on what you said, my theory is just a possibility and is completely unprovable right now. BUT, if any of her neighbours weren't woken up at all... Could it be possible that someone murdered her using a gun that has a suppressor and that the walls were thick enough to mask most of the sound to prevent anyone else from waking up?"

Bakugo's eyes widen, unable to hide his surprise. It is a possibility, and it isn't far fetched either. He clearly remembers that the gun on the apartment floor doesn't have a silencer. What else could explain a bullet being fired going unheard? But then, this is solely based on IF there is a murderer (although what they technically have now points in that direction...). 

Bakugo grabs the pillow carefully and turns on his heels, walking out the door.

"We need to check the gun, the pillow, and the body. She could've died from suffocation but the murderer made it look like a suicide", Bakugo mumbles. Kirishima smiles and follows him. 

-

Bakugo barges into his lab (he demanded he owned one) while dropping all of his things on the floor, Kirishima following behind him (technically, it's his too now).

Bakugo strips the pillow of its case and places it into the vacuum chamber. He hasn't used this method in a while but he remembers it as clear as day. 

The VMD (Vacuum Metal Deposition) method can be used to find fingerprints on cloth and any smooth surfaces which include using several alloys (Zinc, Gold, Tin, Aluminium and more). The gold is heated up and evaporated to spread a fine film over the fabric. Then, the zinc is heated up and it will attach to the gold, where there are no fingerprint residues. This helps reveal the fingerprint. 

If there was contact, it will show the original fabric. If there wasn't, it'll be grey (you'll be left with the grey color of the metal film, to be specific).  

Kirishima sits on a chair near the table, turning the gun delicately in his gloved hands, squinting at it closely. 

"There's dirt on the gun… it's faint but it's there… is that grass?" Bakugo hears him mumble. 

"What grass?"

Bakugo walks over and leans down next to him, squinting as he stares at the trigger where Kirishima was pointing at. 

"Yeah, it's grass…", he mumbles. 

Both of them look at the machine. Fingerprints are appearing slowly on the screen and Kirishima takes out his phone to snap a picture. 

"Grass, slight dirt on gun… fingerprints on the pillow… Was she suffocated then shot? The gun was placed next to her on the floor, with her fingerprints on it? To make it look like a suicide…", Kirishima asks. 

He closes his eyes for a moment before letting out a surprised "oh". 

"And I heard you mumble her fingernails were slightly chipped and there was dirt underneath it and little specks of blood, you were loud enough when explaining that part, thankfully. If she was clawing at the murderer, would that mean the murderer has been to somewhere that has dirt and grass? Or maybe he fell down… or is it…", Kirishima starts muttering. 

He stops before standing up and walking out of the room, waving a hand behind him. "Let’s go check on the body!"

Bakugo sighs and follows him. Kirishima has brains surprisingly, both of his theories are both quite valid after all.

He looks up to see the idiot bouncing  down the corridor and he questions if Aizawa actually gave him a tour or not. 

"This way idiot", he says, heading to the left. 

Kirishima stops before jogging up to Bakugo. 

"Right, sorry!" 

Bakugo shoves his hands in his pockets. "It's alright, dumbass." 

I really hope there aren't any grammar errors in here, even after I checked it-
Edit:
The same thing happened and I had the most pleasurable pain fixing and re-reading everything ^-^ +

I was RE READING IT AGAIN and I had to check my notes on the blood staining pillow part because apparently, I left that part out...

Which led to Bakugo speculating thick walls... And one thing led to another and now we have this...

I hope nothing is too confusing for you guys -