Gabriela finally decided to talk to Arvin directly. She felt the need to get more information about Arvin's relationship with Catherine and anyone else who might be related to the tragic death.

When break time came, Gabriela approached Arvin in his classroom and said in a polite tone, 'Arvin, I need to talk for a minute. It's important.'

Arvin looked a little confused but finally agreed. Gabriela took him to a quieter place in the schoolyard, under a large tree that other students rarely passed by. However, before Gabriela could start talking, a girl suddenly appeared. The girl looked hurried, her eyes sharply directed at Gabriela.

'Arvin, what are you doing here with her?' the girl asked in a sharp tone, making Arvin look even more agitated.

Gabriela observed the girl. She was wearing a neat uniform with her long hair tied up neatly. Her face showed obvious dislike, not only for the situation, but also for Gabriela in particular.

'Melissa, calm down, she just wants to talk for a minute,' Arvin said, trying to calm the girl down.

However, Melissa didn't look calm at all. She folded her arms across her chest and said, 'If she wants to talk, why not in front of everyone? Why does it have to be here, alone? What does she really want from you, Arvin?'

Gabriela felt that the atmosphere was becoming increasingly uncomfortable, but she didn't want to prolong the conflict. She looked at Melissa calmly.

'I'm sorry if I misunderstood you. I just wanted to ask you something about Catherine,' Gabriela said in as friendly a tone as possible.

However, Melissa's reaction changed drastically at the mention of Catherine's name. Her face instantly paled, then her eyes narrowed. 'Catherine? Why are you suddenly bringing her up?' she asked, her voice colder now.

Gabriela noticed the change, but she remained calm. 'There are some things I want to know about her. It's important,' Gabriela replied.

Melissa looked like she wanted to reply, but Arvin interrupted her. 'Melissa, I can explain later. It'll just take a minute, okay?'

Melissa sighed loudly, then said, 'Fine, but not for long.' With a suspicious look at Gabriela, she finally turned around and left.

After Melissa was far enough away, Gabriela turned towards Arvin. 'Who is she?' asked Gabriela, holding back her curiosity.

Arvin scratched the back of his head, looking embarrassed. ''She's... my close friend. I know, he gets jealous easily, but he's actually a good person.'

Gabriela wasn't sure about that judgement, especially after seeing Melissa's reaction just now. However, she chose not to comment on their relationship. Instead, she focused on her goal.

'I just want to know more about Catherine,' Gabriela said. 'You guys had a quarrel before she died, right? Was it because of Melissa?'

Arvin's face immediately showed guilt. He nodded slowly. 'Yes. Catherine feels that I got too close to Melissa. But it was just a misunderstanding. I just knew Melissa for a long time before we started dating."

Gabriela pondered. Melissa looked so emotional just because Gabriela was talking to Arvin. Perhaps, her jealousy was deeper than it seemed.

'Did Melissa ever meet Catherine after you guys fought?' Gabriela asked carefully.

Arvin seemed to think for a moment, then said, 'I don't know for sure, but Melissa once said she wanted to talk directly to Catherine to "solve the problem". But I don't know what happened after that.'

Gabriela felt that Melissa held the key to this mystery. Her jealousy and emotional reactions were unnatural, and could be related to what happened to Catherine.

'Thank you, Arvin. If I need any more help, I'll call you,' Gabriela said before walking away.

Gabriela walked slowly back to her classroom, feeling the dead end suffocating her mind even more. The fact that Catherine died by being hit from behind, without any witnesses or clear evidence, made Gabriela wonder if she could really help Catherine's spirit find justice.

'Can Melissa really lose her mind just because of jealousy?' Gabriela thought, trying to connect all the pieces of information she had. But every time she thought of Melissa, she felt that something didn't fit. There was no real evidence. Melissa was emotional and jealous, but was that enough to make her a murderer?

Gabriela sat on her stool, staring blankly ahead. 'If Catherine herself doesn't know who killed her, how am I supposed to know?' she muttered, frustrated. She was beginning to feel desperate. No clear clues, no concrete answers, just an increasingly complicated puzzle.

The bell rang, signalling the end of the school day. Gabriela packed her things languidly. Walking outside, she passed the large tree where Catherine had first appeared. She paused for a moment, hoping that perhaps Catherine would appear again to give her a clue. But the tree was silent.

Gabriela let out a long sigh. 'I'm sorry, Catherine. I tried, but I didn't know where else to go.' Gabriela said to herself, feeling like a failure.

However, that night, as she sat at her study table at home, something came to her mind. Catherine died from a blow to the back of the head, but what object was used? Was it found? If not, it might still be around the scene.

Gabriela quickly grabbed her small notebook, wrote down the idea, and decided to return to the site of the former police line behind the school tomorrow. There might be something she missed, something that could be a clue.

With a small hope rekindled, Gabriela promised herself that she would not give up so easily. 'I have to try one more time,' she murmured, staring at the locket she had found. 'Catherine deserves justice.'

Gabriela decided to go to the regional police station...gabriela stepped steadily into the regional police station. The air inside was stale, filled with the smell of stale coffee and old papers. The reception desk at the front was manned by a tired-faced officer who looked at her with curious eyes. Gabriela sighed for a moment before summoning the courage to speak.

'Good afternoon, sir. I'm Gabriela, a student from Surabaya International School. I would like to ask you about a murder case that happened around our school,' she said in a polite but firm tone.

The officer frowned. 'You're a student? What's your interest in that case? This is serious business, kid, not to be messed with.'

Gabriela bit her lip. 'I know, sir, but I... have a reason. The victim is my classmate. I just want to know what really happened.'

The officer looked doubtful, but finally gave a small nod. 'Just a moment,' he said as he walked to the back room.

A few minutes later, a policeman in a neat uniform appeared. His name was written on his chest: Kompol Agus. He looked at Gabriela with a sharp but not intimidating gaze. 'You want to know about Catherine's case, yes? Okay, but we can only give you basic information. What do you want to know?'

Gabriela sat down in the chair provided. Her voice was almost a whisper when she said, 'I want to know what the police know about the killer. Is there any evidence? Or eyewitnesses?'

Kompol Agus took a deep breath before answering. 'This case is complicated, son. Catherine was found dead near the back area of the school, with a blunt force injury to the head. No fingerprints, no DNA. There's only one witness, a resident who claims to have seen someone leaving the scene around the time of the incident.'

Gabriela tilted her head. 'Someone? Who? What are their characteristics?'

'The resident said it was a man, using a sports bike, a Kawasaki Ninja. Unfortunately, since it was late afternoon, his face was not clearly visible. There is no CCTV footage around the area, so our leads are very limited.'

Hearing that, Gabriela felt her heart beat faster. 'A sports bike? Could the culprit have something to do with our school?' she asked quietly.

Kompol ( komisari polisi /the police commissioner) Agus looked at her deeply. 'We don't have any evidence that leads to that. But, if you know something, you should report it, not investigate on your own. This is the job of the police, not students like you.'

Gabriela nodded, though her mind was spinning. She knew the police had limitations without further evidence. However, she had something others didn't: the spirit of Catherine that continued to haunt her.

As Gabriela walked out of the police station, the afternoon breeze hit her in the face, bringing with it the wet scent of freshly rained tarmac. She felt like her mind was full of questions. Who was the man on the sports bike? Was it Arvin?