Apprehension is fear or anxiety about something, like the apprehension you feel about an upcoming test. Apprehension is also the capture of a criminal — that is, when the criminal is apprehended. Finally, apprehension can mean one's understanding of an idea. Get it?
Given the crook's record of evading arrest, the chief had real apprehensions about being able to catch him. Eventually though, she activated the whole police force in an effort to ensure the crook's apprehension. And it paid off! They caught him red-handed. But it wasn't until he saw the video of the crime in progress that the guy apprehended just how much trouble he was in. It was that apprehension that led him to make a deal with the district attorney.