The police are investigating the cause of the crash.
The police are investigating the murder.
They are investigating the mystery of the universe thoroughly.
Well, there's something I'd like your advice on about my research project ... "Let's see... Hmm, you're investigating flowering plants then."
When investigating the pH (acidic, neutral, alkaline) of a liquid, don't soak the litmus paper completely in the liquid but just put the end of the paper in it.
The police are investigating the cause of the crash around the clock.
The police are investigating my brother for the murder, but they're barking up the wrong tree.
Corpora provide a rich resource for investigating language.
The investigating committee is looking into the cause of the accident.