This is what the Nakamoto family now has to worry about. It wasn't a random killing. There were at least 6 people arrested in connection with the murders. Apparently the robbers had people inside the bank who they were paying to alert them whenever someone withdrew large amounts of cash.
People get killed over money a lot. It's probably not paranoia. I would recommend you watch the video to understand the gruesome nature of what Nakamoto now has to live with.