Updated at 4:15 p.m. Oct. 19:
On Friday, Illinois State Police spokeswoman DeAnn Falat said the investigation is ongoing, and no further information was available.
"I have been advised that it is still under investigation by our investigators in Zone 3," Falat said in an email to Patch.
Visitation for Knudsen, a Plainfield Central High School graduate and employee at Mickey O'Neill's in downtown Plainfield, was scheduled for Friday. Funeral services were scheduled for Saturday morning in Plainfield.
READ: SERVICES SCHEDULED FOR RYAN KNUDSEN
Illinois State Police said they are still investigating why a pedestrian was in the roadway when he was struck and killed on Interstate 55 near Plainfield.
Ryan A. Knudsen, 22, died early Sunday after being struck by a semi-tractor-trailer in the right line of northbound I-55, just north of the U.S. 30 Joliet/Plainfield exit. A second vehicle traveling behind the semi also struck Knudsen, according to police.
Knudsen was pronounced dead at the scene at 6:10 a.m., according to Will County Coroner Pat O’Neil.
O’Neil said an autopsy was performed Monday confirming Knudsen's cause of death as multiple injuries sustained in the crash. But he said the manner of death is pending the outcome of the state police investigation and toxicology results.
O’Neil noted there are currently no indications that drugs or alcohol played a role in the incident, but said it could take several weeks to get test results.
A spokeswoman for the Illinois State Police said the investigation was ongoing, and could not say why Knudsen was in the roadway on Sunday.
“That’s still all under investigation,” she said.