Billy Brown and Brea Grant will join the Season 6 cast of Showtime's hit drama "Dexter."

As no-nonsense homicide detective Mike Cutler, Brown (“Death Row,” "Southland") will ignite tensions at the office as his character transfers from Chicago.

Grant's ("Heroes," "Halloween II") character is currently unknown; however, some rumors indicate she may be a lab intern.

Brown and Grant are part of several new cast additions, including "Battlestar Galactica" star Edward James Olmos, Colin Hanks ("The Good Guys") and rapper Mos.

The series follows a serial killer (Michael C. Hall) who holds a job as a Miami police forensics specialist while quenching his thirst for the kill by hunting criminals who he believes have escaped justice.

Production on Season 6 is already underway to meet a fall premiere.

"Dexter" also stars Jennifer Carpenter, C.S. Lee, James Remar, Desmond Harrington.