Who killed Markiplier?

I trust no one

  You followed the enraged man as he climbed up the stairs that you and the Detective had once done while talking of who killed Markiplier. "Where is he?!" The Colonel fumed. He dashed up the carpet steps, skipping a few here and there. "He took them from me, he took my friends from me!" His tone of voice wavered, the words of the Butler about him being in pain came back to you now. And you could hear the pain in his voice from his next words. "He took, Celine." The Colonel huffed up the stairs, "He took, Damien!" he turned into a small hallway with twin doors on each side. "Where is he?!" The Colonel flug open one of the doors, "Where is he?!" He yelled opening the other. "Detective!" You put a shaking hand out to him, "Are you hiding him from me?!" The Colonel brushed past you to one more door, "He can't hide forever, get out of my way!" He pushed aside. The Colonel marched down the hallway where everyone once was, at the end of the hallway, was the Detective. He was fidgeting with the lock on the door to the room where you had last seen Celine. "Detective!" The Colonel pointed his gun at the man in question. The Detective answered by pulling out his own gun. You had a quick chance to look around you. It was dark, was it night? How did that happen? "You better choose your next words carefully, Colonel." The Detective aimed at the Colonel. "Only my friends get to call me by that name and you, sir, are no friend of mine!" The Colonel snapped back at the Detective. Who laughed sardonically at the Colonel's weak insult, "You're one to talk about friends you murder!" The Detective sarcastically mocked him with thunder clapping in the background, as if it was watching a boxing match. "I didn't kill anybody! This is madness!" The Colonel paused for a split second. "You wanna talk about madness?" The Detective's voice seemed to raise in pitch slightly. You felt like you had heard this before, "Madnesses is stealing your best friend's wife!" The Detective yelled at the Colonel. Celine must have been married to Mark, that's how she knew him. And that's why the Colonel was so flippant about Mark's death in the first place, he didn't care about him. You reached out to the Colonel, putting a hand on his shoulder. He only pushed you off. Before the Colonel had a chance to counter the Detective, he cried again. "Madness is squeezing him for cash to fund your own sick sexual exploits with that very woman!" It seems the Detective did had taps on Celine and the Colonel. "Shut up!" The Colonel had slowly pushed the Detective up against the wall, each man had no intentions of letting the other man go, even if that made them a murder. Thunder and lighting stormed even though no one had summoned it. The Detective drew breath, "Madness is plotting the death of your childhood friend because you can't handle the tr-" A gunshot interrupted him. The Detective was slouched over in pain, and after a few seconds, he was dead. You moved to see if he really was, but seemed to get tangled up with the Colonel. His finger must have still been on the trigger, as it slipped and fired another shot. This time the  bullet it hit you, you looked down to your hands only to see them soaked in blood. The world around you grew bright, dizzying. You could make out the fine line of the Colonel. Who reached for you as you suddenly began to fall backwards. You had fallen over the railing, a disfigured voice called out to you. "It was an accident!" It must have been the Colonel, he was the only one left. The last  thing you saw was the chandelier, and the only noise was the crunch of bones and the Colonel's words
"I swear!"