Complex sentence: Detective Hal Slocumb (Keitel) discovers the event that Louise experienced in Texas, and during a couple of brief phone conversations, expresses sympathy for her predicament and pledges to protect her, but he is unsuccessful in his attempts to persuade her to surrender.
Split into simpler sentences: Detective Hal Slocumb (Keitel) discovers the event that Louise experienced in Texas, and during a couple of brief phone conversations, expresses sympathy for her predicament and pledges to protect her. But he is unsuccessful in his attempts to persuade her to surrender.