kare ha muzitu da to itta.

The basic structure is:

[彼は無実だ] と 言った。

• 彼は無実だ = the content being said
• と = quotation marker
• 言った = said

So the sentence is literally something like:

[He is innocent] + said

Also, in normal Japanese writing, this would usually be written without spaces:

彼は無実だと言った。

と marks the content of speech or thought.

With 言う (to say), it often works like English that or like quotation marks.

So in:

彼は無実だと言った

the と tells you that 彼は無実だ is what was said.

A very common pattern is:

• plain sentence + と言う = say that ...

Examples:

• 行くと言った = said that someone would go / said I’ll go
• 大丈夫だと言った = said that it was okay

Because 無実 is not a verb or -i adjective. It behaves like a noun-type predicate, so it needs the copula だ in plain style.

• 無実 = innocence / innocent
• 無実だ = is innocent

So:

• 彼は無実だ = he is innocent

You cannot normally just say 彼は無実と言った if you mean said that he was innocent.
You need だ to complete the predicate before と.

Not exactly in the same way as an English adjective.

In Japanese grammar, 無実 is basically a noun-like word that can be used predicatively with だ.

So:

• 無実だ = is innocent
• 無実の人 = an innocent person

This is why it patterns differently from an -i adjective like 高い.

Compare:

• 高いと言った = said it is expensive/high
• 無実だと言った = said he is innocent

は marks 彼 as the topic: as for him...

So 彼は無実だ presents him as the person being talked about.

If you used が instead, it would sound more focused or contrastive, as if identifying him specifically:

• 彼は無実だ = as for him, he is innocent
• 彼が無実だ = he is the one who is innocent

In many contexts, both are possible, but は is a very natural default if the sentence is simply about him.

Japanese often leaves the subject of 言った unstated if it is clear from context.

So this sentence by itself does not explicitly say who did the saying.

That means the sentence could be understood as something like:

• He said he was innocent
• Someone said that he was innocent

depending on context.

Grammatically, the only explicit 彼 here is inside the quoted content: 彼は無実だ.

Japanese is often less strict about this distinction than English.

彼は無実だと言った can function like reported speech, but the structure is still literally a quotation of content.

So depending on context, it can feel like:

• He said, He is innocent
• He said that he was innocent

In natural translation, English usually uses indirect speech here, but Japanese does not always force a sharp line between direct and indirect quotation in the same way.

Because the tense of the main verb and the tense inside the quotation are handled separately.

• 言った = the act of saying happened in the past
• だ = the quoted statement itself is in plain non-past form

Japanese does not always shift tense inside reported speech the way English often does.

So even if English says:

• He said that he was innocent

Japanese can still use:

• 無実だと言った

rather than automatically changing it to a past form.

Yes, but that would change the meaning.

• 無実だと言った = said that he is / was innocent
• 無実だったと言った = said that he was innocent

The difference depends on the time reference inside the quoted content.

Japanese lets you choose the tense inside the quotation based on what the speaker meant, not just based on the tense of 言った.

Because this sentence is in plain style.

Before と言った, Japanese usually uses the plain form of the quoted sentence when simply reporting content:

• 彼は無実だと言った

If you use です, it sounds more like you are preserving the politeness of the original speech:

• 彼は無実ですと言った

That can be possible, but it feels more like an actual quoted utterance in polite style.
For a neutral report, だ is more typical.

Yes, if the context already makes it clear who is being talked about.

Japanese often omits information that is understood.

So you could have:

• 無実だと言った = said that he/she was innocent / said I’m innocent / said that it was innocent

The exact meaning would depend heavily on context.
Adding 彼は makes the referent explicit.

Yes, in casual speech.

• 彼は無実だって言った

This is a more conversational version of と.

In writing or more neutral standard grammar explanations, と is the basic form to learn first:

• 彼は無実だと言った

Not necessarily.

By itself, 彼は無実だと言った only tells you that the quoted content is he is innocent.
It does not guarantee whether the speaker and 彼 are the same person.

Context decides that.

So this could mean either:

• He said that he was innocent
• Someone said that he was innocent

Japanese often leaves that kind of reference for context to resolve.

A very literal breakdown would be:

• 彼は = as for him
• 無実だ = is innocent
• と = quoting marker
• 言った = said

So, very literally:

Said, He is innocent.

That is not natural English, of course, but it shows how the Japanese pieces fit together.