Was Dexter Ever Caught?

In "The British Invasion", Doakes finally catches Dexter in the act of disposing of a dismembered body in the Florida Everglades.

Did they find out Dexter was a killer?

Despite Dexter Morgan's secrecy, there were characters who became aware that he was a serial killer, or suspected him of murder. By the end of the series, only four were still alive, with seven being directly murdered by Dexter.

Does anyone find out Dexter's secret?

In the first season, it was revealed that Brian knew Dexter's secret, and eventually tried to lure Dexter into killing full time. Dexter ended up killing him and making it look like a suicide after Brian kidnapped Deb.