According to a recently released memo he wrote to his personal assistant, John Lennon already had notions of a possible threat on his life, months before he was murdered.
"Explain to me why we are sleeping here with a front door that any nut can open (it doesn't lock)," he wrote in the note dated April 28, 1980. "People know I'm here- gardeners, painters, etc."
His anxiety and frustration is clearly evident in his agitated ending directive to assistant Fred Seaman: "You're usually last in at nite you better check."
Lennon was killed seven months later on December 8, 1980 when Mark David Chapman shot him in the back four times in the entrance of the Dakota, his residence at the time.