keisatu ga syouko wo mitukemasita.

It is read:

けいさつ が しょうこ を みつけました。

Word by word:

• 警察 = けいさつ
• が
• 証拠 = しょうこ
• を
• 見つけました = みつけました

が marks the subject of the sentence, meaning the one who did the action.

So in this sentence:

• 警察が = the police is the one that performed the action

A very literal breakdown is:

• 警察が = the police (subject)
• 証拠を = evidence (object)
• 見つけました = found

So が tells you who found the evidence.

を marks the direct object, meaning the thing directly affected by the action.

Here:

• 証拠を = the evidence as the thing that was found

So:

• 警察が = the police
• 証拠を = the evidence
• 見つけました = found

This is a very common pattern in Japanese:

X が Y を verb

= X does the verb to Y

Both can be possible in Japanese, but they give slightly different feelings.

• 警察が証拠を見つけました。
  This focuses on the police as the ones who found it, or presents that as new information.

• 警察は証拠を見つけました。
  This would make the police the topic, as if you are already talking about them, and now you are saying what they did.

Very roughly:

• が = subject focus / new or important information
• は = topic / something already under discussion or contrasted

For learners, it is enough to know that が is perfectly natural here.

見つけました is the polite past form of the verb 見つける.

• dictionary form: 見つける = to find
• polite non-past: 見つけます
• polite past: 見つけました

So 見つけました means:

• found
• or more literally, did find

It is polite because of the -ます ending.

It is both:

• past tense
• polite style

Japanese often combines tense and politeness in the verb form.

So 見つけました tells you:

1. the action is completed / in the past
2. the speaker is speaking politely

A casual version would be:

• 警察が証拠を見つけた。

Japanese normally uses Subject-Object-Verb order, unlike English, which usually uses Subject-Verb-Object.

English:

• The police found evidence.

Japanese:

• 警察が 証拠を 見つけました。
• literally: The police evidence found.

So it is normal in Japanese for the verb to come last.

警察 usually means the police as an institution or body, not necessarily one specific officer.

It can refer to:

• the police in general
• the police authorities
• the police as the group responsible

If you want to clearly say a police officer, you would often use:

• 警察官 = police officer

So this sentence sounds more like:

• the police found the evidence than
• a single police officer found the evidence

No, Japanese does not use articles like a, an, and the in the same way English does.

So:

• 警察 could be the police
• 証拠 could be evidence or the evidence

You understand the exact meaning from context.

That is why a Japanese sentence can feel more flexible or less specific than an English translation.

By itself, 証拠 does not tell you clearly whether it is singular or plural.

It can mean:

• evidence
• a piece of evidence
• the evidence

Japanese nouns usually do not change form for plural the way English nouns do.

If the speaker wanted to make plurality clearer, they would usually do it through context or by adding other words.

This is a very common question because both use the kanji 見.

• 見る（みる） = to see, to look at
• 見つける（みつける） = to find, to discover, to spot

So:

• 証拠を見ました = saw the evidence
• 証拠を見つけました = found the evidence

Even though they share the kanji 見, they are different verbs.

This is an important distinction.

• 見つけました = found
  This focuses on the person/agent who found something.
  It is a transitive verb.

• 見つかりました = was found / turned up
  This focuses on the thing that was found.
  It is an intransitive verb.

Compare:

• 警察が証拠を見つけました。
  = The police found the evidence.

• 証拠が見つかりました。
  = The evidence was found.

So your original sentence emphasizes who found it.

Sometimes yes, because the particles show each word’s role.

For example, these can still be understood:

• 証拠を警察が見つけました。
• 警察が証拠を見つけました。

Because:

• が still marks the subject
• を still marks the object

However, not every rearrangement sounds equally natural in every context. The original order is a very normal and straightforward one.

They are usually added only for learners.

Normal Japanese is normally written without spaces:

警察が証拠を見つけました。

Textbooks and beginner materials often add spaces to make the sentence structure easier to see.

It is polite, but not extremely formal.

The politeness comes from 見つけました.

It would fit many neutral situations, such as:

• classroom examples
• polite conversation
• news-style explanations
• simple written statements

A more casual version would be:

• 警察が証拠を見つけた。

A more formal or written style might use different wording depending on context.