How to say "investigate" in Japanese

• 調べるしらべるJLPT N4approx.Common
  ichidan verb, transitive verbThe general-purpose choice: to examine, check, or look into something, from looking up a fact to looking into a matter. Covers both casual fact-checking and a serious inquiry.
  ココの知能指数ちのうしすうを調しらべるのは容易よういではない。↗

  Testing Koko's IQ is not easy.
• 取り調べるとりしらべるJLPT N1approx.Common
  ichidan verb, transitive verbOfficial investigation by an authority, especially the police questioning a suspect or working a case. This is the word for interrogation-style investigation, not for everyday checking or looking things up.
  事件じけんの原因げんいんを取り調とりしらべるために実情じつじょう調査ちょうさ委員会いいんかいが作つくられた。↗

  A fact-finding committee was set up to determine the cause of the incident.
• 洗うあらうJLPT N5approx.Common
  godan verb, transitive verbLiterally 'to wash'; used idiomatically for investigating in the sense of combing or sifting through something thoroughly. Not the plain, everyday word for a general inquiry.
• 探るさぐるJLPT N2approx.Common
  godan verb, transitive verbInvestigating by probing: feeling one's way into something unknown, spying on, or sounding out a person's intentions or a situation. Exploratory and often discreet rather than systematic.
  遠とおまわしに彼かれの意見いけんを探さぐった。↗

  I sounded him out about his views.
• 尋ねるたずねるJLPT N4approx.Common
  ichidan verb, transitive verbSeldom the word you want for 'investigate': its core senses are to ask a question and to call on or visit someone, and the 'look into' sense is marginal.

Use 「調べる」 for general examining or looking up, 「取り調べる」 for official police questioning, 「探る」 for probing or sounding out, 「洗う」 for combing through thoroughly, and avoid 「尋ねる」, which mainly means to ask or visit.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 調べるしらべるto examine
• 取り調べるとりしらべるto investigate
• 探りを入れるさぐりをいれるto probe
• 洗うあらうto inquire into
• 探るさぐるto investigate
• 案じるあんじるto investigate
• 尋ねるたずねるto search
• 掘り下げるほりさげるto dig into (a matter)
• 案ずるあんずるto investigate