Der Richter verurteilt den Angeklagten.

Because they are in different cases:

• der Richter is the subject of the sentence, so it is in the nominative case.
• den Angeklagten is the direct object, so it is in the accusative case.

In German, articles often change to show the job of the noun in the sentence:

• der = masculine nominative
• den = masculine accusative

So the sentence structure is:

• Der Richter = the judge
• verurteilt = convicts / sentences
• den Angeklagten = the defendant / accused person

German often shows this through case marking, not just word order.

Here:

• der Richter is nominative, so he is the one doing the action.
• den Angeklagten is accusative, so he is the one receiving the action.

So even if you are still getting used to German word order, the articles help you identify the roles.

This is a major difference from English, where word order usually does most of that work.

verurteilt is the 3rd person singular present tense form of the verb verurteilen.

The infinitive is:

• verurteilen = to convict / to sentence

The present-tense conjugation is:

• ich verurteile
• du verurteilst
• er/sie/es verurteilt
• wir verurteilen
• ihr verurteilt
• sie/Sie verurteilen

So Der Richter verurteilt den Angeklagten means The judge convicts/sentences the defendant.

In this sentence, it is present tense, not a past participle.

Why?

Because it is the main finite verb in second position:

• Der Richter verurteilt den Angeklagten.

A past participle would usually appear with an auxiliary verb such as hat:

• Der Richter hat den Angeklagten verurteilt.
  = The judge has convicted the defendant.

So although verurteilt can also be a past participle, in this sentence it is clearly the present-tense verb.

Because Angeklagte is one of those masculine nouns that takes an extra ending in certain cases. This is often called the weak masculine pattern.

Its forms are:

• nominative: der Angeklagte
• accusative: den Angeklagten
• dative: dem Angeklagten
• genitive: des Angeklagten

So in your sentence, because it is the direct object after den, it becomes den Angeklagten.

This is very common with nouns referring to people, especially ones that originally look adjective-like, such as:

• der Deutsche → den Deutschen
• der Bekannte → den Bekannten
• der Angeklagte → den Angeklagten

Because it is a nominalized adjective/participle — in other words, a word that originally behaves like an adjective but is being used as a noun.

So:

• angeklagt = accused
• der Angeklagte = the accused person / the defendant

German does this a lot. When an adjective or participle is used as a noun, it is capitalized and declines like an adjective in that noun slot.

That is why Angeklagten is capitalized and has an ending.

Because all nouns are capitalized in German.

That includes:

• ordinary nouns like Richter
• nominalized adjectives/participles like Angeklagte

So capitalization is not optional here. It is a standard spelling rule.

Yes, but the verb still usually stays in second position in a main clause.

The neutral order is:

• Der Richter verurteilt den Angeklagten.

You can also say:

• Den Angeklagten verurteilt der Richter.

That version puts more emphasis on den Angeklagten. It is less neutral, but grammatically possible.

Because the cases are marked, German can move elements around more freely than English, as long as the sentence still follows German word-order rules.

Because Richter is just a regular masculine noun here in the nominative singular.

Its form stays:

• der Richter in nominative
• den Richter in accusative

Unlike Angeklagte, it does not belong to that adjective-like pattern with -e / -en in the same way.

So the noun itself stays Richter; only the article changes when needed.

Grammatically, der Richter is the masculine form and traditionally refers to a male judge.

The feminine form is:

• die Richterin = female judge

In some contexts, masculine job titles can be used more generically, but if you are reading the sentence literally and grammatically, der Richter is masculine.

Likewise:

• der Angeklagte = male defendant / accused man
• die Angeklagte = female defendant / accused woman

Yes. The German present tense often covers both:

• convicts
• is convicting

Which English version sounds best depends on context.

So Der Richter verurteilt den Angeklagten could be translated as:

• The judge convicts the defendant
• The judge is convicting the defendant
• The judge sentences the defendant

German does not require a separate progressive form the way English often does.

A useful comparison is English pronouns:

• he vs him
• she vs her
• they vs them

For example:

• He sees him.

English only shows this clearly in pronouns, but German does it much more widely through articles and noun phrases.

So in your sentence:

• der Richter is like he
• den Angeklagten is like him

That is not a word-for-word translation, but it is a good way to understand the case difference.