Excuse my potentially insensitive wording.
He wasn’t studying course materials or writing a true thesis, that was secondary. He was studying how to kill people based on the information he was gathering & playing perpetrator with his new USMC backup weapon.
Going forward, I’m thinking out loud a bit. This whole t-shirt around the knife thing. If he’s already planned to strip off the outerwear, no point in picking something up which could be potential evidence in a victim’s shirt is there? He’d have to know he was going to get messy - just wipe the blade on a leg or sleeve or chest. Much easier & no wasting time looking for this wrapping. If I’m carrying a knife to stab people who are likely asleep, the knife is going to be in stabbing position, downward & along my forearm, not pointing up as if I’m preparing a fine vegan meal with a chef’s knife or stab upwards or forward - I’m in a house where occupants should be asleep. I’m stabbing down. Maybe that vacuum looking attachment was just the knife?
Here’s something to ponder from a selfie I just took. What does this vacuum cleaner attachment look like when carried as shown (or in "chef" position for that matter)? A little short but the profile is strikingly similar to Brybry’s new toy from Amazon.
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Spitballing, JMO.