McHenry County sheriff's deputy Dwight Maness died from a blood clot in his lungs, a Tuesday autopsy determined.
Coroner Anne Majewski said Maness was stricken with cardiac arrest during a Monday rehabilitation session.
Maness, 47, of McHenry, was taken to Centegra Hospital-McHenry, where he died at 1:34 p.m., almost a year after he was shot while on duty.
State's Attorney Lou Bianchi said he suspects that the blood clot may have been a result of his injuries sustained from the shooting, "but it's too early to tell." Accordingly, authorities plan to launch a "manner of death" investigation.
Because Maness had been recovering for almost a year, Bianchi said, officials will also consider his medical records and talk to his family.
"My understanding is that he was starting to use the leg he had been shot in," Bianchi said. "He had also started to drive. There's no question that he was on the mend and working very hard at recovering."
If Maness' death is determined to have stemmed from his injuries, the man who shot him, Scott B. Peters, could be tried again on murder charges, Bianchi said. In June, Peters, 52, was sentenced to 135 years in prison.
Maness' death came nearly 11 months after he and his partner, 39-year-old Khalia Satkiewicz, were shot while responding to a domestic violence disturbance in Holiday Hills.
During that Oct. 16, 2014 call, Peters opened fire and shot Maness in the abdomen and twice in the left leg with a .223-caliber AR15 rifle. Maness, a seven-year department veteran and a former Army ranger, underwent several surgeries and was recovering from his injuries.
On Sept. 2, Maness posted an update on Facebook, saying his right leg had healed significantly. A bone graft in his left leg had taken, he wrote, and the bone was growing.
"The doctor said I can start putting at least 50 percent of my weight on my left leg and can finally start rehab next week," the post said. "Thanks to all of my friends, family (and) the department for the continued support."
The investigation of Maness' death has been turned over to the McHenry County Major Investigation Assistance Team, according to a statement released Tuesday by the sheriff's office.
"The request was in accordance with MCSO policy and effectively removes the sheriff's office from the role of investigating the death of one of our own employees," the statement says, adding that Maness' family and the sheriff's office are making funeral arrangements.
"Thank you for continuing to respect the family, providing them space to gather and grieve."