Possible Clues:

• Lame excuse
• Excuse
• Evasion by policeman not at home?
• Shirker's excuse
• Pretext
• Failure to face some difficulty squarely
• Weak excuse
• Avoidance of responsibility, hence joint expression of annoyance?
• Look annoyed after pacifist's cowardly stance
• Dereliction of duty makes top officer scowl