Simon nodded and said to Vivian, "Currently, we can only start investigating from this delivery man. We need to test whether the substance on the package he delivered is human blood. I will take the items and surveillance footage back to the police station. Please be careful."

Vivian nodded with a frown. "Let me know if there are any updates."

Simon thought for a moment and said, "Let's wait for the results first. I will arrange for two people to keep an eye on your ...