The disassembly condition is a necessary inference from the fact that the shooter is carrying a floppy object (probably a backpack) when he jumps off the roof. Some people have said that he's actually carrying a long rifle, but that object then appears to bend when he runs across the lawn.
Some people did think the FBI stated that the shooter disassembled the gun, but you're right they never said that. They said he ASSEMBLED it on the roof with a screwdriver. That doesn't make sense either but that's a whole other can of worms.
The disassembly condition is a necessary inference from the fact that the shooter is carrying a floppy object (probably a backpack) when he jumps off the roof. Some people have said that he's actually carrying a long rifle, but that object then appears to bend when he runs across the lawn.
Some people did think the FBI stated that the shooter disassembled the gun, but you're right they never said that. They said he ASSEMBLED it on the roof with a screwdriver. That doesn't make sense either but that's a whole other can of worms.