'Prison Break' actor joins 'True Blood'

Marshall Allman set to play Sam Trammell's brother

Marshall Allman is joining the cast of HBO's "True Blood" as a regular for the show's third season.

Meanwhile, Shannon Lucio has landed a guest role on the vampire drama.

Allman will play Tommy Mickens, the long-lost younger brother of Sam Merlotte (Sam Trammell) who works at a Tire Depot in Arkansas.

He is the second new series regular cast on Alan Ball's drama following the hire of Denis O'Hare as Russell Edgington, the Vampire King of Mississippi.

Lucio will play Caroline Compton, the wife of Bill Compton (Stephen Moyer) who lived during the Civil War. Amber Dawn Landrum played the character in a flashback on the show's first season.

Production on the third season of "Blood" begins this week in Los Angeles.

Allman, a series regular on Fox's "Prison Break," playing the teenage son of Lincoln Burrows (Dominic Purcell), recently guest-starred on AMC's "Mad Men" and FX's "It's Always Sunny in Philadelphia."

The actor, whose feature credits include "The Immaculate Conception of Little Dizzle," is repped by Gersh.

Lucio has recurred on "Grey's Anatomy" and "Prison Break."