Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture the tweeter's mental state.
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