Complex sentence: U.S. officials tell Jessie and Roy about Carlos's criminal history, but they don't know anything about Abby; they think she is just a twenty-year-old who got mixed up with the wrong guy.
Split into simpler sentences: U.S. officials tell Jessie and Roy about Carlos's criminal history. The officials don't know anything about Abby and report that she is just a twenty-year-old who got mixed up with the wrong guy.