Complex sentence: Some of the suspects were born outside the U.S., but all are U.S. citizens; however, the U.S. embassy in Pakistan said one of them did not have a U.S. passport.
Split into simpler sentences: Some of the suspects were born outside the U.S., but all are U.S. citizens. However, the U.S. embassy in Pakistan said one of them did not have a U.S. passport.