Etterforskningen fortsetter.

Because etterforskningen is the definite singular form of the noun.

• etterforskning = investigation / an investigation
• etterforskningen = the investigation

This noun is feminine in Norwegian, but in Bokmål many feminine nouns can also take the masculine definite ending -en, so etterforskningen is completely normal.

You may also sometimes see etterforskninga, which is another valid definite form in Bokmål for a feminine noun.

fortsetter is a verb in the present tense.

The infinitive is å fortsette, meaning to continue.

So:

• å fortsette = to continue
• fortsetter = continues / is continuing

In this sentence, it means continues or is continuing, depending on how natural English would express it.

Because Norwegian usually does not need a separate verb like is to form the present tense in sentences like this.

English often says:

• The investigation continues
• The investigation is continuing

Norwegian uses the simple present:

• Etterforskningen fortsetter

So fortsetter can cover both continues and is continuing, depending on context.

Etterforskningen fortsetter is the normal word order for a statement:

• subject
  • verb

So:

• Etterforskningen = subject
• fortsetter = verb

If you say Fortsetter etterforskningen?, that would usually be a question:

• Is the investigation continuing?
• Does the investigation continue?

So the word order changes depending on whether you are making a statement or asking a question.

It is traditionally a feminine noun.

That means you can have forms like:

• ei etterforskning = an investigation
• etterforskninga = the investigation

But in Bokmål, many feminine nouns can also be treated like masculine nouns:

• en etterforskning
• etterforskningen

That is why etterforskningen is correct and very common.

A rough guide for English speakers is:

ET-ter-fors-kning-en

A few helpful points:

• tt is pronounced as a clear t
• rskn in the middle can feel heavy, so it helps to say it slowly at first
• the ng in -ning is like the ng in sing
• the final -en is usually an unstressed ending

The main stress is near the beginning, on ET.

A rough approximation might be:

ET-ter-FORSHK-ning-en

Exact pronunciation varies a little by dialect.

Yes. å fortsette is the normal verb for to continue.

In most contexts, fortsetter simply means:

• continues
• is continuing
• sometimes goes on

So Etterforskningen fortsetter could sound natural in English as:

• The investigation continues.
• The investigation is ongoing.
• The investigation is continuing.

Yes, and it is a very natural alternative.

• Etterforskningen fortsetter = The investigation continues
• Etterforskningen er fortsatt i gang = The investigation is still underway / still ongoing

The original sentence is shorter and more direct. The alternative sounds a little more descriptive.

The infinitive is å fortsette.

Examples:

• De vil fortsette etterforskningen. = They will continue the investigation.
• Etterforskningen må fortsette. = The investigation must continue.
• Hun fortsetter å jobbe. = She continues to work.

So in your sentence, fortsetter is just the present-tense form of å fortsette.

It is neutral and quite common in news, police reports, and formal updates.

Because etterforskning is a somewhat formal word, the whole sentence feels like something you might read in:

• a newspaper article
• an official statement
• a crime report

It is not unnatural in speech, but it sounds more official than everyday casual conversation.