This matter is straightforward. The questioner is troubled for a reason. It likely has to do with how they've felt about this classmate in the past. To resolve this, they need to understand their emotions.
I firmly believe that regardless of how strong the bond between the two individuals was in the past, it is only a reflection of what once was. It does not necessarily indicate that it remains unchanged in the present. After all, individuals' perspectives evolve with age and shifts in the social landscape, and a certain stage of thinking cannot be sustained indefinitely. If the questioner adheres to the same mindset and approach from their school days when examining their classmates and the dynamics between them, they will inevitably face the current challenges and be unable to comprehend some of their classmates' actions.
Being able to work means being an adult, and adults have to take responsibility for their actions. Stealing from others is already illegal, and it's not something that children can just take for fun. Such behavior also reflects a lack of boundaries in his mind with others. He treats other people's things as if they were his own, taking what he wants without considering other people's feelings or the consequences it will bring to himself.
I've been in a similar situation before. A colleague in the same dormitory took the more than 100 yuan I had placed under the mat while I was taking a shower. When I returned from the shower, I found it was gone. I asked him, but he denied any knowledge of it. At the time, he was the only one in the dormitory. I knew he'd spent a lot of money on medical treatment during that period of time and was living a very tight life and needed money, so I told him that I was going downstairs to the police station to report the matter.
I stayed downstairs for about half an hour before coming back. He told me he found it under the mat. I didn't say anything. I knew he'd found it, and I knew he'd returned it. He was worried, scared, and struggling internally. That's enough to offset any responsibility for his behavior.
I believe the original poster should speak with him. Ask him if he is having difficulties in life. Tell him about losing your things. Ask if he knows about it. Tell him that if he loses things again, he should report it to the security guard at the factory or call the police. Give him a warning. It is up to him whether he takes it seriously and makes corrections. He needs to face this problem and think about it. No one else can assume responsibility for it.


Comments
I can't believe he would resort to stealing from me, of all people. I'm going to have a serious conversation with him and demand an explanation for why my belongings were in his suitcase and pantry. If this is true, it's unacceptable behavior and cannot continue.
This situation is so frustrating. First the noise and not taking out the trash, now this? I think I need to gather proof of my missing items being with him and then calmly address the issue with him. It's important to handle this maturely but firmly.
Finding my things in his possession is unbelievable. As classmates, I had trust in him. I'll start by asking him directly about the items I found. If he doesn't give a good reason, I may need to escalate this to someone higher up or even consider legal action if necessary.
It's hard to confront a former classmate, but enough is enough. I will first ensure I have all facts straight and then sit down with him to discuss everything that's been happening. Hopefully, we can resolve this without making it worse between us.
I feel betrayed by his actions. Before doing anything, I want to make sure I didn't make a mistake. Once I confirm everything, I will talk to him about the stolen items. If he admits it, maybe we can find a way to reconcile; if not, I'll have to decide whether to report this to our unit's management.