Complex sentence: The campus police originally suspected that Smart had gone on an unannounced vacation, as was common among students over the holidays, and as a result the campus police were slow in reporting her as a missing person to local law enforcement.
Split into simpler sentences: The campus police originally suspected that Smart had gone on an unannounced vacation, as was common among students over the holidays. It was because of this that the campus police were slow at reporting her as a missing person to local law enforcement.