Task: Categorize the tweet's emotional expression, classifying it as either 'neutral or no emotion' or as one or more of the specified emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that reflect the tweeter's state of mind.
Tweet: @mikeburke91 @AP I guess. It's just heartbreaking the ease with which they can kill an innocent man and get away with it.
This tweet contains emotions: 
anger, disgust, pessimism, sadness