Answer:
The Non-interference of field-study vs the civil obligation.
Explanation:
If you look at this from an academical angle you could argue that, as a neutral and objective field-worker who is gathering information, the researcher did the right thing because of the non-interference he/she applies.
But if you look at the goal of the study (reducing crimes) and the civil obligation every person in this country has, you can only reach the conclusion that the researcher, for one moment putting his civil jacket on, should have reported to the police.