| Reason |
| Purpose |
| Incentive |
| Inducement |
| Whodunit why |
| Driving force? |
| Whodunit's why |
| Mystery element |
| Sleuth's object |
| Whodunit reason |
| Whodunit element |
| Criminal's 'why' |
| Stimulus or goal |
| Cause for a crime |
| Columbo's concern |
| Criminal's reason |
| Reason for action |
| Concern for Poirot |
| Reason for a crime |
| Whodunit necessity |
| Whodunit component |
| Mystery-plot element |
| Whodunit plot element |
| Issue in a murder trial |
| Trial attorney's concern |
| Reasoning behind a crime |
| Murder mystery necessity |
| Detective's determination |
| Greed or revenge, perhaps |
| Incitement to do something |
| Envy, anger or greed, maybe |
| Aspect of a crime investigation |
| Accompanier of means and opportunity |