Learn Polish: W nieoficjalnej wypowiedzi prokurator potwierdził zdarzenie. - In an unofficial statement, the prosecutor confirmed the incident.

You would say: Potwierdziwszy zdarzenie, prokurator.... Notice that because the past tense stem of potwierdzić ends in a vowel (potwierdzi-ł), it takes the -wszy suffix. The -łszy suffix you are currently studying is reserved for verbs whose past stems end in a consonant, such as zjadł becoming zjadszy.

Why does the word for statement (wypowiedź) change to 'wypowiedzi' in this sentence?

The preposition w (in) requires the locative case here. Wypowiedź is a feminine noun that ends in a soft consonant (-ź). For these nouns, the locative ending is -i, and Polish spelling rules dictate that ź combined with i is written as dzi.

Could I use 'wydarzenie' instead of 'zdarzenie' for the word 'incident'?

They translate similarly, but zdarzenie fits the context of a prosecutor much better. A zdarzenie is typically an unexpected incident, accident, or random occurrence. A wydarzenie implies a planned, notable, or organized event, like a concert or a historical milestone.

Why is 'w nieoficjalnej wypowiedzi' placed at the very beginning of the sentence?

Polish frequently uses word order for emphasis rather than strict grammar. Placing this prepositional phrase at the start sets the scene and highlights the context (the unofficial nature of the statement) before introducing the main subject and action. This is a very natural flow in journalistic or formal writing.