Why John Lennon was killed? MIND PROBLEMS? HEART PROBLEMS? CONSPIRICY? VEGEANCE? Why the attemp to kill him and his family?

1 -http://pt.wikipedia.org/wiki/John_Lennon
2 - http://www.johnlennon.com/
3 - http://en.wikipedia.org/wiki/Death_of_John_Lennon
4 - http://answers.yahoo.com/question/index?qid=20081227153355AAJxG1T
5 - http://news.bbc.co.uk/2/hi/entertainment/1060306.stm
6 - http://www.shroomery.org/forums/showflat.php/Number/14190409
7 - http://www.john-lennon.com/theassassinationofjl.htm
8 - http://en.wikipedia.org/wiki/John_F._Kennedy_assassination
9 - http://www.jfkmurdersolved.com/jfkwhy.htm
10 - http://www.coverups.com/jfk/who.htm
11 - http://news.bbc.co.uk/onthisday/hi/dates/stories/november/22/newsid_2451000/2451143.stm
12 - http://www.youtube.com/watch?v=IkEIWN-T_m8