Learn Spanish (Latin America): El sospechoso que escapa es el ladrón. - The suspect who is escaping is the thief.

In Spanish, que is the most common relative pronoun and can mean "that," "which," or "who." Even when referring to people, que is perfectly correct and very common for linking clauses right next to the noun (like el sospechoso que...). While quien also means "who," que is used much more frequently in everyday speech for this type of sentence.

The English translation says "is escaping", but escapa is the simple present tense. Why not use está escapando?

The simple present tense in Spanish (escapa) often translates to the "-ing" form in English. While you could say que está escapando to strongly emphasize that the action is happening right this exact second, native speakers frequently just use the simple present for ongoing actions.

Is sospechoso a noun or an adjective here?

It acts as a noun here, meaning "the suspect." However, it is also an adjective meaning "suspicious." In Spanish, you can easily turn adjectives into nouns by placing an article like el or la in front of them. By saying el sospechoso, you are essentially saying "the suspicious person."

Why do we use es instead of está for the word "is"?