SPRINGFIELD, Ill. (WAND) - Nathaniel Onsrud was convicted in 2008 of murdering his infant son, but work done by the Illinois Innocence Project and the University of Illinois Springfield has now helped set him free.
The Rock Island County man was convicted of murder in 2008.
Newly discovered evidence proves he was not responsible for the death, officials said.
Exculpatory documents were not disclosed to defense counsel that provided additional evidence that Onsrud is innocent.
The Rock Island County State's Attorney's Office supported requests made that Onsrud's conviction be vacated and he be released immediately.
Onsrud served 13 years behind bars.
In May 2007, his 4-month-old son, Dax, became unresponsive while Onsrud was caring for him. The baby was born ten weeks premature and had significant medical complications.
After receiving emergency medical treatment at home, Dax was rushed to the hospital, where he was pronounced dead a short time later.
Officials said initial medical examinations did not suggest foul play, and the forensic pathologist brought in to consult on the case was reluctant to rule the death a homicide.
Officials with the Innocence Project said investigators had multiple meetings with the pathologist and came up with a theory that Onsrud caused his son's death.
They said Onsrud was interviewed twice and after continual questioning, made some "ambiguous statements" that investigators determined was a confession.
Onsrud's defense attorney at the time encouraged him to plead guilty due to that alleged confession.
The National Registry of Exonerations reports false confessions played a role in the wrongful convictions of 96 people in Illinois since 1989.
Onsrud is the 15th client of the Illinois Innocence Project to be released or exonerated.