Here's my theory about the song, first the lyrics:

I Shot The Sheriff

Bob Marley

I shot the sheriff, but I didn't shoot no deputy
Oh, no, oh
I shot the sheriff, but I didn't shoot no deputy
Ooh, ooh, ooh Yeah

All around in my hometown
They're tryin' to track me down, yeah
They say they want to bring me in guilty
For the killing of a deputy, for the life of a deputy
But I say, oh, now, now...

Oh, I shot the sheriff, but I swear it was in self defense
Ooh, ooh, ooh
I said, I shot the sheriff, Oh Lord
And they say it is a capital offense
Ooh, ooh, ooh
Hear this

Sheriff John Brown always hated me
For what I don't know
Ev'ry time I plant a seed
He said, "Kill it before it grows."
He said, "Kill them before they grow."

And so, oh, now, now,
Read it in the news

I shot the sheriff, but I swear it was in self defense
Ooh, ooh, ooh
Where was the deputy?
I said I shot the sheriff but I swear it was in self defense

Freedom came my way one day
And I started out of town, yeah!
All of a sudden I saw Sheriff John Brown
Aiming to shoot me down
So I shot, I shot, I shot him down
And I say, if I am guilty I will pay

I shot the sheriff, but I say, but I didn't shoot no deputy
Ooh, no, oh
I shot the sheriff, but I didn't shoot no deputy
Ooo, ooo, ooh

Reflexes had the better of me
And what is to be must be
Ev'ry day the bucket a-go-a well
One day the bottom a-go drop out
One day the bottom a-go drop out
I say, I, I, ...

I, I shot the sheriff, but I didn't shoot the deputy, no
I, I shot the sheriff, but I didn't shoot the deputy, no

Okay, here's what happened.

We are in time of slavery or legalized segregation. The house is a small two room house and the living room is cramped. About 20 men sit around nervously in intense discussion. The host's children cuddle nervously in the corner and his wife and other women feign discussion and house work as they listen in. The windows are shut as is the door and a couple of men sit upfront as though non-chalantly, though they really are sentinels.

The sheriff and his deputy have been reported killed and witnesses say it was a black man, possibly Bob. The black community knows that there will be hell to pay and they need to know what to do, or at least, what really happened. Finally, Bob admits, that he killed the Sheriff but not the deputy. The distinction is hopeless, killing either one is murder nonetheless. However, Bob insists that there is a story behind the killing. The men shift in place nervoulsy, knowing that if they are caught in the presence of the murderer, they could be charged with conspiracy. And this is a capital offense.

Bob chides the injustice of the system that presumes him guilty even before a hearing or trial. It is then he tells all present that the killing was in self defense. Self defense? How? They ask incredulously. He tells them how Sheriff John Brown always hated him, for no particular reason. He suspects it is because he was an educated black man and thus a threat. He further tells them how whenever he tried to teach other black men and women and especially children how to read, the sheriff always interrupted his efforts and took steps to destroy the seeds that he had planted.

But how does that help your case? they ask. He responds, ask yourselves the questions, where was the deputy when the Sheriff was shot? The deputy was generally considered a good man, a just man, respected by both black and white alike. He treated the black population with respect and they all liked him and were devastated by his death. He had often prevented lynchings and other injustices. What do you mean, where was the deputy? They ask. He was with the Sheriff when they both got killed, right? Bob responds. He continues.

Here's what happened. The other day I was heading out of town. I had my belongs in a sack and my rifle to hunt for food. It was a beautiful day and I was singing and whistling, thinking of my few days of relaxation. I had just crossed the road on the county line and was headed into the path through the woods. All of a sudden I noticed to my left at a distance, Sheriff John Brown aiming to shoot me down. Standing next to him was the deputy. As he was about to squeeze the trigger, I noticed that the deputy yelled at him, what are you doing? The sheriff was undeterred about killing me. It was then that the deputy grabbed the sheriff to stop him and the sheriff shot him and killed him. I then knew that I was next and my only recourse was to shoot him and so I shot him down.

Bob continued . . . I was scared, my reflexes got the better of me and I accept whatever punishment I deserve for killing the sheriff, but I swear I did not kill the deputy. As he was speaking, the door burst open and all the men in the center of the room cleared leaving Bob exposed. it was the authorities. Bob looked around and he understood what had happened. His brothers had called the police. He understood, if he wasn't apprehended then the entire community was at risk. As they dragged him out, he yelled out continuously, I shot the sheriff but not the deputy . . .