Telly didn't kill his parents or the people at the convenience store. Sandra Duvall had a secret past. One where she left her crime boss father when she was sixteen and never looked back. When she left she took the account number for her father's secret off-shore account with $20 Million in ill-gotten funds. When her father died of cancer - Sandra lost the one thing her father offered her - a protection of sorts from his colleagues who wanted to get their hands on that money. They were the ones who killed the Duvall and then the one guy killed his accomplice in the gas station. At the very end it is revealed that it was Sharlah that killed their mother, not Telly.
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