German prosecutors have charged a teenager whom they believe was involved in the plan to attack a Taylor Swift concert in Vienna, Austria, last year, The Associated Press reports. According to prosecutors, the young man—a Syrian national living in Germany who is identified as Mohammad A.—had pledged his allegiance to the Islamic State terrorist group and assisted the main suspect by translating bomb-building instructions from Arabic. Mohammad A. is not in custody because he is a minor.

Swift called off three shows in Vienna last August after police were informed of a credible threat against the concerts, all set to take place at the city’s Ernst-Happel-Stadion. Nearly 200,000 people had been expected to attend the concerts.

Police arrested two people in connection with the alleged terror plot. The main suspect, an Austrian man who was 19 at the time of his arrest, remains in custody. The second suspect, who was 17 at the time of his arrest, has since been released without charge.