'Investigate Something' or 'Investigate into Something'? Which One Is Correct? | Mastering Grammar

Investigate or Investigate Into: Which One Is Correct?

The verb investigate is a transitive verb, which means it takes a direct object. Therefore, it should not be followed by the preposition into. Here are some examples to illustrate this:

✅ We should investigate all possible solutions before making a decision.
❌ We should investigate into all possible solutions before making a decision.

✅ The police are investigating the cause of the fire.
❌ The police are investigating into the cause of the fire.

✅ The detectives investigated the crime scene thoroughly.
❌ The detectives investigated into the crime scene thoroughly.

✅ Researchers are investigating new treatments for cancer.
❌ Researchers are investigating into new treatments for cancer.

This common mistake likely stems from confusion between the verb investigate and its noun form, investigation. While the verb does not include the preposition into after it, the noun often does. For example:

✅ The police launched an investigation into the robbery.

✅ The company is conducting an internal investigation into the allegations.

✅ The investigation into the accident showed that it was caused by human error.

✅ The government promised a transparent investigation into the scandal.

An Informal Alternative: Look Into

In more casual or informal contexts, you can use the phrasal verb look into, which has a similar meaning to investigate. Here are some examples:

✅ The manager will look into the issue and get back to you.

✅ The police are currently looking into the suspicious activity reported last night.

✅ She looked into the matter thoroughly before making her decision.

✅ They have looked into the complaint and resolved it.

You can use into with the noun investigation, but not with the verb investigate.

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Examples from the Media

The Competition Bureau said in a news release Monday that it plans to investigate various issues "with the goal of recommending measures that governments can take to help improve competition in the sector." —Toronto Star (2022)

Police are investigating whether an acid attack on a 14-year-old girl was linked to a dispute at her school, her family has said. —Daily Mail (2024)

The corporate watchdog has launched an investigation into Westpac over potential legal breaches linked to the bank's money laundering compliance scandal, as chairman Lindsay Maxsted commenced critical meetings with investors and proxy advisers. —The Sydney Morning Herald (2019)

The Federal Trade Commission has opened an investigation into whether Microsoft has violated antitrust law in multiple segments of its wide-ranging business, according to two people familiar with the inquiry, the latest salvo in a battle by the government to rein in the most powerful tech companies. —The New York Times (2024)

A review of Dunedin Public Libraries will look into ways to reduce pressure on staff. —Otago Daily Times (2022)

The PSNI is looking into an incident alleged to have taken place during a team trip to the USA. —Belfast Telegraph (2024)