The word "apprehend" means to catch. We use it to talk about police catching criminals, suspects, fugitives, and so on:
Police have apprehended a man suspected of robbing a couple at gunpoint in the waterfront district.
This is a somewhat formal or technical-sounding word. It's mostly used by police officers, government officials, and in the news. In normal conversation, use "catch" instead:
Have they caught the guy who did it yet?