Long-running CBS series "CSI" is bidding adieu after 15 long years. The series finale will be a two-hour special that will be aired live on CBS at 9 pm EST.

Click here to watch the finale online live. 

The series finale will bring back bygone stars such as Marg Helgenberger, who played the role of a stripper-turned-investigator named Catherine, and William Petersen, who essayed the role of Gil Grissom.

So what contributed to the success of the show? According to Ted Danson, who joined the series in Season 12 as "DB" Russell, the unique treatment of solving crime is the prime factor.

The show focuses on how a group of forensic experts at the Las Vegas Crime Lab try probe the evidence set before them to solve murder cases.

"The show had a new way of coming at crime and murder and mayhem," he was quoted as saying by the Associated Press. "Taking a scientific point of view on a crime show was new back then, and allowed viewers into the darker side of life in a way that wasn't just cops-and-robbers."

The two-hour special will see a bomber threatening the safety of Las Vegas citizens and this will force former CSIs Gil Grissom and Catherine Willows and Det. Jim Brass to assist the team to solve the case. Grissom's longtime friend Lady Heather becomes the prime suspect in the case.

As for how the finale will end, Danson revealed that the series has made sure to give fans an opportunity to say goodbye to the people they fell in love with. He also described the ending as "very satisfying."

Other stars who will be featured in the finale will be Jorja Fox, Eric Szmanda, Robert David Hall, Paul Guilfoyle, Wallace Langham, David Berman, Elisabeth Harnois and Jon Wellner.

Although the show is ending its 15 season run, it is launching numerous spin-offs, which include CSI: NY, CSI: Miami and CSI: Cyber.