next question: Following a killing, what are the police likely to begin?
Options:
- man hunt
- punishment
- going to jail
- retribution
- investigation
reasoning:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Investigation is an official examination of the facts about a situation, crime, etc. Following a killing, police are likely to begin investigation. The answer is investigation.