Transcript of audio file:

I guess I can cross Tilly off the list, too. She's got an alibi, she didn't move from that ticket booth all night. Plus, she gave me yet another envelope, said it was slipped through the window when she turned to get a new roll of tickets. Which can only mean one thing: the perpetrator HAS to be tall enough to reach the window slot. That eliminates most small children and babies as suspects. Narrows the field. I feel like I'm making progress. What do I have? I have one suspect, and over 1000 ankle-biting non-suspects. And this envelope. I'm getting close.