Jake knew Brett's house perfectly because he went to Brett's house the night before Brett's murder. Jake knew the layouts, and where to go. Jake kidnapped Tyler by duct-taping Tyler to a chair in Brett's backyard, and eviscerated Tyler with a hunting knife.
Piper was recording Brett, and sending Brett texts, while Jake snuck in to get his kill. Brett was about 5'5", and the killer was several inches taller than him, which fits in with Jake at 6'1". Jake murdered Brett, but both were there. Jake also murdered Tyler.