Chapter 12: Hidden Clues

Night fell, and the town was swallowed by darkness. Irene sat in the police station office, with case materials and documents piled up in front of her. She had been working continuously for more than ten hours. Her eyes were bloodshot, but she showed no sign of stopping.

During the investigation, she found that before each case occurred, the victim would receive a mysterious letter. The contents of the letters were all threatening words, warning them to pay for what they had done. Irene studied these letters carefully, from the texture of the paper to the composition of the ink, from the strokes of the handwriting to the wording of the letters, trying to find clues.

"These letters must have been sent by the killer, but how did he manage to leave no trace?" Irene muttered to herself. She checked a large number of surveillance videos and interviewed countless witnesses, but to no avail. The killer was like a ghost, acting quietly in the dark without leaving a single trace.

Just when Irene was feeling desperate, Maria found her. Maria looked hasty and took out a small recording device from her bosom, handing it to Irene. "This was recorded by me in the confessional. A drug dealer's confession. He mentioned 'the Butterfly' and'sacrifices'," she said.

Irene's eyes lit up instantly. She couldn't wait to press the play button. The trembling voice of the drug dealer came from the recording, "They said the butterfly needs more sacrifices. Those sinners can't escape..." Irene's heart raced. She realized that this might be the most important clue so far.

She and Maria sat in a coffee shop near the police station. The steaming coffee in the cups gave off a fragrant smell, but no one paid any attention. The two began to carefully analyze the recording content, pondering over every word. "It seems that this 'Butterfly' organization is closely related to these cases, and their targets seem to be those who were involved in covering up the steel factory pollution incident back then," Irene said. Maria nodded, her eyes showing concern. "But who are the people behind this organization? Why do they punish these people in such a cruel way?"

Irene fell into deep thought. The figures of Carl and those related to the steel factory and the orphanage emerged in her mind. She knew that the truth was among these people. What she had to do was piece together these scattered clues and uncover the truth behind it.