Part 4: Suspicions and Revelations

Emma and Detective Reed stood outside the student center, bracing against the cool morning air. They had interviewed several of Nathan's friends, each conversation shedding a little more light on his final days. Yet, one person remained elusive: Sarah. Despite her grief, something about her recent behavior struck Emma as odd.

Detective Reed noticed Emma's hesitation. "You seem troubled. What's on your mind?"

Emma glanced at him, her expression conflicted. "It's Sarah. She and Nathan were so close, but lately, she's been avoiding us. I can't help but feel like she knows more than she's letting on."

Reed nodded. "Let's talk to her. We need every piece of this puzzle."

They found Sarah in the campus café, sitting alone with a cup of coffee, her eyes red from crying. She looked up as they approached, her expression guarded.

"Sarah, can we talk?" Emma asked gently, sitting across from her. Reed took the seat next to her, his presence calm but authoritative.

Sarah nodded, her hands trembling slightly. "I've already told the police everything I know."

"We appreciate that," Reed said, his voice steady. "But we have a few more questions. We're trying to understand what Nathan was going through. Can you help us?"

Sarah sighed, her eyes welling up with tears. "Nathan was... he was scared. He wouldn't tell me why, but I knew something was wrong. He became so distant."

Emma leaned forward. "Sarah, we found some encrypted files on Nathan's laptop. Files that suggest he was being blackmailed. Did he ever mention anything about that?"

Sarah's face went pale. "Blackmailed? No, he never said anything about that. But he did ask me once if I had any money saved up. He said it was for an emergency. I thought it was strange, but he wouldn't explain."

Reed's eyes narrowed. "Did you give him the money?"

Sarah shook her head. "I offered, but he refused. Said he'd figure it out."

Emma's mind raced. "Sarah, we found messages on Nathan's phone from an unknown number, threatening him. Do you know anything about that?"

Sarah's hands clenched around her coffee cup. "I didn't know about the threats, but I did see him with a new phone a few weeks ago. He said his old one was acting up, but now I'm wondering if it was something else."

Reed took a deep breath. "Sarah, we need to be honest with each other. Is there anything, anything at all, that you haven't told us?"

Tears streamed down Sarah's face. "I loved Nathan. I would never do anything to hurt him. But... there was one thing. A few days before he died, he gave me a USB drive. He said if anything happened to him, I should give it to someone I trust."

Emma and Reed exchanged a look of surprise. "Do you still have it?" Emma asked urgently.

Sarah nodded, fumbling in her bag. She pulled out a small USB drive and handed it to Reed. "I didn't know what to do with it. I was scared."

Reed took the drive carefully. "You did the right thing, Sarah. We'll look into this."

Back at the station, Reed and Emma plugged the USB drive into a secure computer. The drive contained several encrypted files, similar to the ones on Nathan's laptop, along with a video message from Nathan.

They opened the video, and Nathan's face appeared on the screen, his expression serious and strained.

"If you're watching this, it means I didn't make it," Nathan began. "I've uncovered something big. Professor Walker is involved in embezzling funds from the university, but it's deeper than that. There are others involved, people with power. I've gathered all the evidence I could, but they're onto me. I'm scared, but I have to see this through. If anything happens to me, please, get this to the authorities. Don't let them get away with it."

The video ended, leaving Emma and Reed in stunned silence. The weight of Nathan's words hung heavily in the air.

Reed spoke first, his voice firm. "We need to decrypt these files and get to the bottom of this. Nathan was on to something huge, and it cost him his life."

Emma nodded, her resolve hardening. "We owe it to Nathan to finish what he started."

Over the next few days, they worked tirelessly to decrypt the files. Mark's skills proved invaluable, and soon they had a clearer picture of the embezzlement scheme. It involved not only Professor Walker but also several high-ranking university officials and local businessmen. The scale of the corruption was staggering.

As they prepared to confront the involved parties, they received an anonymous tip: a meeting was scheduled that night at an abandoned warehouse on the outskirts of town. The tipster claimed it was where the final transaction would take place, sealing the fate of the stolen funds.

Reed and Emma, along with a team of officers, decided to stake out the location. The warehouse was dark and foreboding, its shadowy interior a perfect setting for clandestine dealings.

As they watched, cars began to arrive, their occupants slipping inside. Reed signaled the team to move in. They entered the warehouse silently, spreading out to cover all exits.

Inside, they found Professor Walker and several other suspects huddled around a table, counting stacks of money. The sight of the police left them stunned and scrambling for explanations.

Reed stepped forward, his voice cold and authoritative. "This is over. You're all under arrest for embezzlement and conspiracy to commit murder."

The look of shock on Walker's face was almost satisfying. As the officers cuffed the suspects, Emma felt a sense of closure. Nathan's killers were finally brought to justice.

But as they led the suspects away, Emma couldn't shake the feeling that there was still something missing, some piece of the puzzle that remained unsolved. She glanced back at the warehouse, wondering what other secrets it held, and what other dangers lay ahead in their quest for the truth.