Checkmate.

The Chase

Detective Knight had been staring intently at the chessboard for the past few minutes. His hands were tightly holding onto the desk, and his eyes were darting from one square to another onto the board. And suddenly, as if something clicked in his mind, he quickly picks up a knight and a queen from the chess pieces and place them on the board.

"When Chelsea was murdered, she had 'B2' carved on her arm and was found with a knight. She was killed 7th Elvia Street, block no. 24." Knight murmurs to himself, and places the knight onto the square B4 on the chessboard. Mark, his assistant, is closely watching his seniors every move, trying to catch up to his theories. 

"When Nick was murdered, he had 'C3' carved and had a queen enclosed in his fist. He was killed at 9th Blue Street, block no. 34." Detective picks up the queen and places it on square B3. His eyes widen when he realises that the knight and queen are on blocks that are diagonal to each other. After the queen, it's always the King. He picks up the king and places it on D4, such that all the three chess pieces form a diagonal. 

"Oh my god." He gasps. The answer was right under their noses all this time. He glances at the watch, and the clock reads, 12:30 am. 

"Mark, what's the closest street to block no. 44 around our murder sights?" 

"On it, give me a second." Mark replies, quickly typing away on his computer. After a few seconds which seemed like hours, he replies,

"11th Amber Street. Why?" 

Without bothering to answer him, Knight quickly grabs the chess board with him and motions Mark to start the car.

"Go, go, go! I'll explain everything on the way, drive to 11th Amber Street, now!" He shouts, impatiently. Mark immediately nods, and hops into the car and starts driving to their destination. 

"It seems like Chelsea and Nick have more than one thing in common. So both of them, were killed in the morning, around this time. Both of them were found with a chess piece, which happened to be a knight and a queen. Both of them had chess square numbers carved on their arms, B2 and C3. When you place these chess pieces on the board, they somehow are forming a diagonal line. It's obvious that as per the sequence, after the queen comes the king. And being part of the diagonal, the king lands on B4. Also, these two victims were killed on blocks no. 24, and 34. And my guess is, there's gonna be a third murder. On 11th Amber Street, block no. 44." Detective Knight explains.

Mark was absolutely appalled. How Detective Knight came up with this plausible theory in such less time, was completely over his head. He kept on driving, increasing his speed, trying to save as much time as possible. He comes to a screeching halt when they reach their destination and slowly shuts off the engine. He looks at his senior and Detective Knight gives him an encouraging nod. The pair tucks out their guns and they stealthily walk towards the block 44. 

Creeping up on the walls of the area, with their guard on, they sneak into a sort of room close by and glance around. When they find nothing, they're about to walk out, when they hear a whimper. On high alert, they walk towards the noise and spot a fragile girl bruised and beaten up, tied to ropes with her mouth covered. Her legs have the similar bruises.  Detective Knight signals Mark to call for back up. Mark nods and walks out to call police. 

Meanwhile Knight bends down and puts a hand on the girls shoulder, trying to calm her down. His ears perk up when he heard a shuffling sound on the other side of the door. He puts a finger on his lips, indicating her to stay silent. He stands up and heads towards the door, with his gun on recoil. He quietly opens the door, begging it not to creak. It doesn't. 

He sneaks inside, and hides behind a pillar. He glances at the young man, sitting on a chair, in front on the chess board. The man looks like he's planning something. Knight can't imagine that this young man, had killed all these innocent people. 

"Looks like you finally found me, Knight." His voice echoes through the room and Detective Knight mentally shivers. 

"I did. And now it's high time you face you fate. How could you do this?" He asks, disgusted.

"It was fun challenging you, I must say." He replies, coolly. 

Detective Knight was about reply, but then a number of police officers barge into the room surrounding the man. He looks at the man, and feels immense satisfaction. 

"You are under arrest for the murder of Chelsea Waters, Nick Manders and the torture of - " He stops, when he realises he doesn't know the name of the girl.

"Kate Mart. That's her name." The murderer replies, not at all fazed.

Chelsea. Nick. Kate. Check Mate. 

"Well then. You are under the arrest for Chelsea Waters, Nick Manders and the torture of Kate Mart. Looks like your plan backfired. Check Mate, you disgusting imbecile."