'Alcatraz' was never a huge hit for FOX, it's series premiere was watched by over 10 million viewers. Since its premiere in January 'Alcatraz' has been streadily dropping in viewers, losing more than half of its audience. The now series finale which aired on March 26 was watched by only four million viewers.
Here is the break down of the last five aired episodes:
Episode 09 - Sonny Burnett - March 5 - 5.47 million viewers
Episode 10 - Clarence Montgomery - March 12 - 5.07 million viewers
Episode 11 - Webb Porter - March 19 - 5.04 million viewers
Episode 12 - Garrett Stillman - March 26 - 4.78 million viewers
Episode 13 - Tommy Madsen (Series Finale) - March 26 - 4.75 million viewers