Using the deciphering of the History Channel (right side) I have attempted to fill in the blanks on the first six lines. The green lettering is from the History Channel. The yellow lettering is my calculated decryption. The pink lettering is far more speculative.
The reasoning behind the opening two words "my thing," is partially derived from the threat on the Dripping Pen card, possibly left as a clue by the killer, and the code itself. The solve reads:
MY THINGS, I KILL BOTH NIGHT AND DAY. I LIVE BY THE GUN BARREL AIM AND LIKE FISHING FOR GOLDFISH OVER PIGS. I MISS GOLDILOCKS NOW.
If you have a better decryption for the pink and yellow areas, please post them in the comments below. The 340 Cipher.