One mistake.

He stared at me with his beautiful green eyes, and sweetly smiled a smile that became so familiar to me. That’s when I pulled the trigger and watched as his deep red blood stained the antique rug. I whispered to his dead body, “I love you and always will.” I pulled the trigger for the final time, but this time in my stomach, so it would be a slow and painful death. It was my punishment.
The last thing I heard was "We have you surrounded, come out of the house".
After a minute a dozen policemen barged in, only to find our dead bodies. After months of being on the run, for theft of the world’s last piece of coal we gave up, but took the easy way out. Like cowards. Once you make one mistake it will follow you for the rest of your life and haunt your memory, and there’s no going back. The police ALWAYS find you, since every person alive has a tracker inside their heads. Your being tracked right now.

170 words.