The Feltscher brothers are half swiss half venezuelan and they both decided to play for Venezuela (they wouldnt have made a game for switzerland though, not good enough)
But maybe you mean Vonlanthen, half colobian, he played for switzerland and made 2004 the record for beeing the youngest goalscorer on an European Championship. But he fucked up his career due to weird religious lifestyle, he joined a cult which didnt allowed him to play football on Saturday

..later he needed money and made his comeback on the pitch, but failed everywhere. Moron.