Who killed Leonard's wife?

Rating: 5/10 (14 May 2001)

It amazes me how many people praise this movie yet still don't get it and fail to grasp the full truth of the story. Because the plot is so complicated in the way it was presented it took my wife and I hours to figure out what really happened. Credit that to the director for having pulled off such an incredible and original movie. ------WARNING***-----SPOILER AHEAD------------- I have read the last 80 comments on this board and not once did anyone observe that Leonard ALREADY had started his body tatooing before his wife died. In an extremely brief scene at the the end of the movie, Leonard is seen laying in bed half-naked with his wife with a few of his tatoos already on his upper chest. This lead me to the following conclusions. 1. Leonard's wife survived the intruders' attack, though Leonard himself suffered severe head trauma which leads to his handicap. 2. As a result of this affliction, Leonard begins tatooing his body, the results which are seen in the final bedroom scene with his wife. 3. Leonard himself kills his own wife with an insulin overdose and then transposes the deed to Sammy Jarkis. The 'real' Sammy never had a wife according to Teddy. Yet in order to justify his 'revenge', Leonard reminds himself that Sammy was a murderer. 4. Leonard is sent to a mental institution (according to the clues in the official website) and begins plotting the murder of the second assailant in his diary. He then escapes the institution and hooks up with Teddy who helps him find the assailant. Teddy photographs the blood-covered Leonard as a reminder of his nasty deed, knowing full well that Leonard will soon forget and continue his killing rampage. 5. Teddy takes advantage of Leonard's affliction and uses him to kill a drug dealer for monetary gains only to be outsmarted by Leonard when he realizes he was duped by Teddy.
Presumably, Leonard will continue his rampage until the authorities eventually catch up with him and puts him away for life.