The Encrypted Massacre Investigation

"Yes, I noticed that as well. Very good deduction." He says, and pulls some notebook paper out of the manilla envelope, handing them to you. "I already deciphered them."

Yhe first note read:
"L, This is your punishment. Kira was rightfully a god, and Aizawa paid for your foolishness. You should have never gotten involved. Next is Matsuda. Kira will prevail.