Complex sentence: Mosley soon disappears, after learning no-one would help him, suspecting the cartel might have influence in the police, a fact Gabriel finds out chillingly when he goes to Mosley's office to retrieve a tracking device.
Split into simpler sentences: Mosley soon disappears, suspecting the cartel might have influence on the police, after learning no-one would help him. Gabriel confirms this chilling truth when he goes to Mosley's office to retrieve a tracking device.