Live

Watch CBSN Live

Is a caregiver in prison for a murder that never happened?

LAKE COUNTY, Ill. -- The story of the young Lake County, Ill. daycare worker, convicted in 2011 of killing a toddler, just keeps getting stranger and stranger....as the murder case against her continues to unravel. And now, in the latest development, the current Lake County coroner Dr. Thomas Rudd says he wonders if a murder occurred at all.

He is so troubled by newly discovered X-rays that he has changed the official manner of death on the child's death certificate.

Sneak peek: Blaming Melissa

This case began in January 2009, when Melissa Calusinski, just 22 at the time, was charged with first-degree murder of 16-month-old toddler Ben Kingan. The charge of murder followed a finding by the pathologist Dr. Eupil Choi that the toddler had a skull fracture that occurred the day of his death. Melissa also confessed to assaulting the child after an unrelenting nine-hour interrogation.

In November, 2011, Melissa was convicted of first-degree murder and sentenced to 31 years in prison. Shortly afterwards, her father, convinced she was innocent, asked Dr. Rudd, the newly elected county coroner, to review her case. Dr. Rudd did, and what he discovered raised the first serious questions about Melissa's conviction.

Dr. Rudd found evidence of an earlier brain injury that the pathologist at autopsy, Dr. Choi, overlooked. After being confronted with the discrepancy, Dr. Choi admitted in an affidavit that he made an error, but later said it would not have changed his testimony at trial.

And then last month, a true bombshell! An anonymous caller told Melissa's father that X-rays existed that had never been seen at trial. Dr. Rudd asked his office to scour the files and to his shock, the X-rays were there.

Those images, taken at the child's autopsy more than six years ago and before Dr. Rudd became the county coroner, appear to show no skull fracture at all. Instead, according to Dr. Rudd, the "new" evidence confirms that Ben Kingan suffered a head injury weeks before Melissa came to work at the daycare center.

These X-rays, says Dr. Rudd, now make it impossible for him to be sure that the child's death was intentional. So, last week, he took the highly unusual step of changing the manner of Ben Kingan's death from "homicide" to "undetermined."

A confession in question

So what now happens to Melissa Calusinski? Will she get a new trial? It is not clear at this point. Her attorney Kathleen Zellner has asked the original trial judge to throw out that conviction and hold a hearing on the case. Lake County State's Attorney Michael Nerheim has not commented on the new developments, but his office released this statement referring to the X-rays:

"We are currently reviewing these documents to determine whether this material had previously been given to the defense, whether this in fact is new material, and whether these images have any added significance to what was previously presented at this defendant's murder trial."

The more we learn about the Melissa Calusinski case, the more questions arise: Why weren't all the autopsy X-rays shown at trial? We know now that there were five X-rays -- the two newly discovered images and three others that were unreadable. All of the images now appear to be easily accessible in the coroner's computer system.

However, at trial, the assistant state's attorney who prosecuted Melissa's case told the judge and the defense team about three X-rays, the unreadable ones. Was it a simple mistake or did someone deliberately withhold the readable images from the defense? Who is the anonymous caller who finally let Melissa's family know the X-rays existed? And why now?

Lake County Circuit Court Judge Daniel Shanes has promised to announce on Sept. 15th whether or not to hold a hearing. There are certain to be more twists and turns in this case ahead.

Erin Moriarty is a "48 Hours" correspondent. She investigates the Melissa Calusinski case during a "48 Hours" double feature starting Saturday at 9 p.m. ET/PT on CBS.