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Prepositions after verbs

How to use “investigate” with prepositions

Investigate usually takes a direct object or is followed by into. The combinations investigate by, investigate in, and investigate for are not standard fixed patterns, although the prepositions may appear with other meanings in a sentence.

Quick answer

Correct use of “investigate”

Use investigate something or investigate into something in some formal contexts. “Investigate by” may describe a method. “Investigate in” usually refers to location or field. “Investigate for” may describe a reason for an investigation.

Police investigated the accident.
The committee investigated into the claims.
Scientists investigated the material by using laser scans.

Choose the pattern by meaning

These forms are not interchangeable. Choose the construction by meaning, not by which preposition appears most often.

1
investigate + object

Examining a situation or problem

Use investigate directly with the thing being examined.

They investigated the complaint immediately.
Reporters investigated the fraud for months.
2
investigate into + issue

Formal investigations

Into sometimes appears in formal or official English.

The agency investigated into the allegations.
Officials investigated into the cause of the fire.
3
investigate by + method

Describing the method used

By can introduce the method of investigation, not the object investigated.

Researchers investigated the damage by comparing old photographs.
The team investigated the case by interviewing witnesses.
4
investigate for + reason

Giving the purpose or cause

For may explain why someone is being investigated.

The company was investigated for tax violations.
He was investigated for fraud last year.

See the difference in context

The same subject can take different constructions because each sentence answers a different question.

Construction
Example
Meaning
investigate something
Detectives investigated the robbery.
Standard and most common structure.
investigate into something
The panel investigated into the incident.
Formal variant used in some official contexts.
investigate by
They investigated the problem by testing each part.
By introduces a method, not a fixed verb-preposition combination.
investigate in
She investigates in the field of genetics.
In can refer to a field or place, not the object of investigate.
investigate for
The official was investigated for corruption.
For introduces the suspected offence or reason.

Common mistakes

Some combinations appear in real text but do not mean what learners often assume.

Adding “in” before the object

Investigate usually takes a direct object.

✕ Police investigated in the accident. ✓ Police investigated the accident.

Using “by” for the object investigated

By introduces a method, not the topic.

✕ They investigated by the fire. ✓ They investigated the fire.

Confusing investigate and search

For is used for reasons, not for the thing examined.

✕ Scientists investigated for the disease. ✓ Scientists investigated the disease.

Quick practice

Choose the expression that matches the intended meaning.

1. The police investigated ___ robbery.
2. The engineer investigated the failure ___ running additional tests.
3. The company was investigated ___ fraud.

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Frequently asked questions

Is “investigate into” correct?

Yes, especially in formal or official English, although investigate something is more direct.

Can I say “investigate by”?

Only when by introduces a method, such as investigate by testing samples.

Do we use “investigate in”?

Not for the object of the investigation. In may refer to a place, area, or field.

identify-with-by-in-as, for "ignore by" or "ignore in"? illuminate by, with, at, for or in? "illustrate by" or "illustrate in"? "imagine for", "imagine by" or "imagine in"? imbue with, in, by or onto? immigrate to, from, in, with or into? impair by, for, in, because or throughout? "impart to", "impart in" or "impart by"? "impeach by" or "impeach for"? "impinge on" or "impinge upon"? "implement in" or "implement by"?

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