My sleuthing had finally led me to the house of the thief.
I climbed the pipe and snuck in through the open window. I saw papers fallen everywhere. I spotted a small collection of musical instruments, probably stolen. Among them, I spotted my guitar. Before I could grab it, I heard footsteps coming up to the room. I quickly hid inside the wardrobe. Through the gap, I saw the thief walk in, pick the guitar and strum it in the most beautiful way. Kudos to him.
I realized that I did not want my guitar anymore. I wanted his autograph.