The original stars of "Prison Break" have become very busy since the serial drama ended and their respective projects might be a delaying factor in the production of "Prison Break" season 5.

Wentworth Miller and Dominic Purcell, who play main characters Michael Scofield and Lincoln Burrows, are held up with their evil ways as Captain Cold and Heatwave in "Legends of Tomorrow." The two first played the "Legends" characters in the TV version of the DC Comics hit "The Flash."

As for female lead Sarah Wayne Callies, "Prison Break" season 5 may have to take a backseat since the actress is currently starring in the USA Network science fiction drama "Colony," which premiered on Jan. 14.

Unlike Miller and Purcell, Callies's return is still up in the air although she has been in talks with FOX about reprising her role as Scofield's wife Dr. Sara Tancredi.

"They're trying to make it work, I'm trying to make it work – it's a bit of Tetris with everyone's schedules because we all have other jobs," Callies told Digital Spy.

The star said that by next month, it will all be finalized.

The "Prison Break" season 5 production is scheduled to begin this spring.

"They're at the script stage right now, and so they're gonna have to know who's in it, where we're gonna do it and when we're gonna do it," Callies explained.

"Prison Break" season 5 is set several years after the events in the fourth season. For the uninitiated, Scofield actually died in the finale although a "logical and believable" explanation for his resurrection will be provided.

The season, which is being described as a sequel to the 2009 film "Prison Break: The Final Break," was originally planned to run for 10 episodes. But according to Express, the length of the season is now uncertain.

"Prison Break" season 5 is expected to premiere later this year or early next year.