You have been commanded by L to follow Light on his daily to make sure he isn't making anything suspicious. But when you were walking down the Mall, Until someone stopped you from behind.

"I am Kira, Don't turn around." The familiar voice spoke while wearing a hoodie that covered him. It was light but you weren't aware

"I'll have to kill the guy with the broom, at your right.. To prove myself to you." And, the guy fell dead. This was all light's plan, he had already investigated by him.