You walk over to Maya's desk. She's staring intently at her shoelaces. "Maya, why are you being so quiet? Did you see who took the cupcakes?"
Maya jumps, looking nervous, then takes a deep, shaky breath. "I... I didn't see them take them," she whispers, leaning closer. "I was getting a drink right before the bell, and I overheard two kids talking outside the room. They were bragging about taking the cupcakes."
She glances nervously at the clock. "They aren't from our class, or even our grade. They're in Mr. Hansen's class upstairs. When they saw me, they stopped and cornered me. They said if I told anyone, they would both point fingers at me and say I was the thief. They said it'd be two against one, and no one would believe me."
Maya's eyes fill with relief that she finally told someone. "But I know I have to tell. It was them, I promise!"
You now have a strong lead: two thieves from Mr. Hansen's class!