WAS KEY EVIDENCE MANIPULATED TO HELP CONVICT A DAYCARE WORKER OF MURDER?

48 HOURS Investigates in "Unraveling the Case Against Melissa" Saturday, Jan. 18 at 10:00 PM, ET/PT

Melissa Calusinski has been behind bars since 2009 when, at the age of 22, she was arrested for murdering 16-month-old Benjamin Kingan at a suburban Chicago daycare center where she worked. She has long maintained her innocence. This week, 48 HOURS returns to a story correspondent Erin Moriarty has been covering for more than a decade with new details in "Unraveling the Case Against Melissa," to be broadcast on Saturday, Jan. 18 (10:00-11:00 PM, ET/PT) on the CBS Television Network and streaming on Paramount+.

Calusinski was convicted and sentenced to 31 years in prison, but her attorneys argue that critical evidence that might have cleared her was manipulated. Now, Calusinski's fate rests with Illinois Governor J.B. Pritzker, who can grant her clemency and set her free.

"This is not where I belong ... I'm gonna continue to fight no matter what 'cause I did not do this," Calusinski tells Moriarty.

Calusinski was the last one with Ben before his death. The pathologist who conducted the autopsy said the child suffered extensive bleeding in his head and a skull fracture on the day he died. The interrogation was grueling. More than 60 times, Calusinski told police she didn't do it, but after nine long hours, she confessed to throwing the toddler on the ground.

"They broke me down," Calusinski tells Moriarty.

Calusinski's defense argues the interrogation was coerced, and that clear x-rays found after the trial prove Benjamin Kingan did not have a skull fracture and that the x-rays the defense was given before trial had been manipulated and darkened. Over the years, prosecutors have stood by their case.

This new episode features exclusive interviews and new revelations, including:

· A rare interview from prison with Calusinski.

· An interview with a woman who worked at the day care with Calusinski, who has never spoken publicly before. She wrote a heartfelt letter to Pritzker advocating for Calusinski's release.

· Computer forensics experts Andrew Garrett and Brian Bowman show Moriarty how they believe key x-rays were manipulated, causing them to be unreadable.

· For the first time, 48 HOURS tracks down and interviews a former daycare employee who was mentioned in connection to a prior head injury Benjamin Kingan sustained. Over the years, Calusinski's defense has argued that a prior head injury further aggravated by Ben's head banging caused the toddler's death, and that Calusinski had nothing to do with it. This daycare employee has never been charged with harming the child - intentionally or accidentally.

· Dr. Saul Kassin, a renowned expert on false confessions, provides insights into why Calusinski may have confessed to a crime she says she didn't commit.

And at 9:00 PM, ET/PT, when a young Minnesota mother goes missing, her sister turns to TikTok for help. 48 HOURS correspondent Peter Van Sant reports in an encore of 48 HOURS: "The Disappearance of Maddi Kingsbury."

Judy Tygard is the executive producer of 48 HOURS. Watch 48 HOURS on CBS News 24/7, CBSNews.com, Paramount+ and YouTube. The 48 HOURS free, advertiser-supported streaming (FAST) channel is available on Pluto TV, Paramount + and Paramount partner channels. Download the CBS News app on your phone or connected TV. Follow 48 HOURS on X, Facebook, TikTok, YouTube and Instagram. Listen to the 48 HOURS collection of original podcasts from CBS News.