"48 HOURS" GOES BEHIND THE SCENES WITH A DEFENSE TEAM AND CUTTING-EDGE FORENSIC ANIMATORS AS THEY STRATEGIZE TO DEFEND A YOUNG WOMAN ACCUSED OF MURDER

See What Happens Before a Case Hits the Courtroom in "The Evidence Room" Saturday, Dec. 23, 9:00-11:00 PM

Tracy Smith and 48 HOURS get an up-close look inside the legal strategy sessions and the creation of cutting-edge animation that happens long before a case hits the courthouse, in "The Evidence Room," a special two-hour edition to be broadcast Saturday, Dec. 23 (9:00-11:00 PM ET/PT) on the CBS Television Network.

Smith goes inside the investigation of a murder case against Colleen McKernan, who was charged with shooting her husband 10 times on New Year's Eve in 2014. McKernan's attorneys claim it was self-defense and hired forensic animator Scott Roder to create visual representations of her story of what happened that night. Roder is a CBS News consultant who agreed to take us inside his investigation.

In criminal court, evidence is everything. It can send a defendant to prison for life or set them free. But before that happens, in this case, the lawyers, their forensic animators, and prosecutors spend countless hours figuring out the best strategy with their individual theories of what happened the night of the murder.

The prosecution says it was a cold-blooded murder. The defense says it was a kill or be-killed situation.

"I look at the totality of the evidence and put it together, kind of like a puzzle," Roder tells Smith of his process. "This isn't about emotion. We evaluate the evidence. We conduct experiments. We reduce it to a visual presentation. And then we try to demonstrate that for the benefit of the jury."

Smith is on hand as Roder uses a gun with live ammunition to see if what McKernan says happened is possible.

Roder is not a lawyer, he's not a detective and he's not a forensic scientist. However, the animations and recreations Roder and his team create can play a significant part in a trial. Roder's work in the case against Olympian Oscar Pistorius was not allowed into court, but it was played worldwide and featured in an edition of 48 HOURS.

Though the team may be hired by either the defense or prosecution, Roder is adamant that he doesn't determine guilt or innocence in his work.

"Well, that's not my job," Roder tells Smith. "That's what the jury does"

Smith and 48 HOURS walk viewers though the sometimes emotional and occasionally frustrating preparations that go on behind closed doors before a jury walks into a courtroom.

Josh Gelman is the senior coordinating producer of 48 HOURS: "The Evidence Room." Leigh Hubner is the producer and the director of photography. Gayanne Keshishyan is the development producer. Alicia Tejada is the field producer. Jeff Pinilla is the editor. Judy Tygard and Peter Schweitzer are the senior producers. Nancy Kramer is the executive story editor. Susan Zirinsky is the senior executive producer.

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