sleuthing

/S L UW1 TH IH0 NG/
verb
  1. 1

    To act as a detective; to try to discover who committed a crime, or, more generally, to solve a mystery.

Synonyms

noun
  1. 1

    Detective work

Source: https://en.wiktionary.org/wiki/sleuth, https://en.wiktionary.org/wiki/sleuthing