Investigating

The police are investigating the cause of the crash.

The police are investigating the cause of the crash around the clock.

The police are investigating the murder.

The police are investigating the cause of the accident.

The police are now investigating the cause of the accident.

The investigating committee is looking into the cause of the accident.

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 my brother for the murder, but they're barking up the wrong tree.