Complex sentence: She began attending the university at 16, but five months into her freshman year she was arrested for purchasing marijuana from an undercover police officer; when she was later arrested for storing stolen property in her dorm room, the University of Colorado decided to expel her.
Split into simpler sentences: She began attending the university at the age of 16; however, five months into her freshman year, she was arrested for purchasing marijuana from an undercover police officer. She was later arrested again, for storing stolen property in her dorm room at which point the University of Colorado decided to expel her.