Dexter is a series on Showtime. They describe the character of Dexter Morgan as:

Miami Metro Police Department blood spatter analyst, leads a double life. When he's not helping the homicide division solve murders, he satisfies his dark desires by hunting and killing bad guys who slip through the justice system.

After the Casey Anthony verdict this afternoon people started posting on the Dexter facebook page like crazy.  See the screenshot below to see some of the posts or visit the fan page here.