המשטרה התחילה חקירה.

In Hebrew, משטרה means the police force / police department, and it is a singular feminine noun.

So Hebrew says:

• המשטרה התחילה... = The police started...

not a plural verb.

This is different from English, where police often takes a plural verb in some varieties of English, like The police are investigating. In Hebrew, משטרה is grammatically singular, so the verb agrees with it in the singular.

Because המשטרה is a feminine singular noun, the verb has to match it.

In the past tense:

• התחיל = he started / masculine singular
• התחילה = she started / feminine singular

Since המשטרה is feminine singular, Hebrew uses התחילה.

התחילה is past tense.

So the sentence is describing something that already happened.

Related forms of the same verb:

• המשטרה מתחילה חקירה = The police is starting / starts an investigation
• המשטרה תתחיל חקירה = The police will start an investigation

In your sentence, התחילה clearly means started.

The prefix ה־ is the Hebrew definite article, meaning the.

So:

• משטרה = police / a police force
• המשטרה = the police

Hebrew usually adds the as a prefix, not as a separate word.

Hebrew normally has no separate word for a or an.

So:

• חקירה can mean an investigation
• החקירה means the investigation

That means the indefiniteness of חקירה is understood automatically because there is no definite article on it.

Because את is used before a definite direct object, and חקירה here is indefinite.

Compare:

• המשטרה התחילה חקירה = The police started an investigation
• המשטרה התחילה את החקירה = The police started the investigation

So no את is needed in your sentence.

A simple pronunciation guide is:

ha-mish-ta-RA hit-khi-LA kha-ki-RA

A few notes:

• ח is a throaty sound, like German ch in Bach
• The stress is usually at the end in all three words:
  • ha-mish-ta-RA
  • hit-khi-LA
  • kha-ki-RA

No. It only looks that way at first.

The verb is from להתחיל = to begin / to start, and its root is ת־ח־ל.

So in התחילה, the first ה is part of the verb pattern, and the ת belongs to the root. It is not the reflexive hitpa’el pattern.

That can be confusing for learners because many hitpa’el verbs also begin with הת־ in writing.

Yes. חקירה is also a feminine singular noun.

You can often spot many feminine nouns by the ending ־ה, though not every noun ending that way is feminine for the same reasons.

If you added an adjective, it would also be feminine singular:

• חקירה ארוכה = a long investigation
• חקירה רצינית = a serious investigation

Yes. This is the basic and very common order:

subject + verb + object

• המשטרה = subject
• התחילה = verb
• חקירה = object

Hebrew can sometimes change word order for style or emphasis, but this sentence is straightforward and natural.

This sentence is grammatical and clear. But in news-style Hebrew, you will also often hear more idiomatic alternatives such as:

• המשטרה פתחה בחקירה = The police opened/launched an investigation
• המשטרה החלה בחקירה = The police began an investigation

So המשטרה התחילה חקירה is understandable and correct, but depending on context, another verb may sound a bit more natural or more formal.

The dictionary form is להתחיל = to start / to begin.

When learning verbs, it helps to connect the forms like this:

• להתחיל = to start
• התחיל = he started
• התחילה = she started
• מתחיל = starting / starts (masculine singular)
• מתחילה = starting / starts (feminine singular)

So in your sentence, התחילה is simply the feminine singular past form of להתחיל.