They do not know what caused the crash, and they're not confident they will ever know the answer to that question.
"It's one of the things we are trying to figure out, but we might never know," said Illinois State Police trooper Joe Dittmer.
The crash happened around 9:15 p.m. Sunday night at the intersection of Rt. 24 and County Road 3360 East near Weston.
Pronounced dead on the scene were 52-year-old Eldon Kaeb and his wife 42-year-old Stephanie Kaeb of Arrowsmith.
Eldon was driving as the couple traveled north, but they failed to stop at a stop sign and slammed into a semi tractor trailer traveling west.
Preliminary autopsy results shows Eldon died of multiple blunt force injuries with a specific concentration to his head and chest areas.
Stephanie also died from multiple blunt force injuries, including the head chest and abdomen.
Coroner Beth Kimmerling said she has ordered toxicology testing, but not because there is evidence of drug or alcohol use by the couple.
"I am fairly certain because of their faith, that is not an option," she said. The Kaebs were Apostolic Christian and belonged to a church in Forrest.
Kimmerling has also ruled out a medical event as a contributing factor to the crash and said only one cell phone was found zipped in Stephanie's purse.
It's not believed Eldon was a drowsy driver, either, since the crash happened within minutes of the couple leaving a family gathering.
"The 911 call came in between 9:15 and 9:20, but the people at that gathering thought the Kaebs left around that same time," Kimmerling said.
It's especially baffling for authorities since they believe the couple was familiar with the intersection.
Kimmerling said, "They traveled the area often. It's not like they didn't know the stop sign was not there."
In fact, the couple was headed to Wisconsin for a side job on a farm when the crash happened. They also had a dairy and grain farm in Arrowsmith.
Family friend and school bus driver for the Ridgeview School District in Colfax, Vickie Doyle, said farming was one of the couple's passions.
"It meant everything to them because the whole family farms. It's deeply rooted in the whole family. Started with their dad," Doyle said.
Doyle was one of a few people in the school district who were remembering the couple and their family Tuesday.
The Kaebs leave behind nine kids, ranging in age from around six to early 20s. Many of them attended Ridgeview before the family decided to home school.
Doyle was their bus driver, and she remembers growing up with Eldon and his 13 brothers and sisters.
"They filled up the bus," she joked.
Ridgeview teacher Carla Taylor was Stephanie's college roommate at Eureka College and knew some of her extended family.
"All I can remember is her smile, and she had a smile from ear to ear," Taylor said.
Taylor also taught some of the Kaebs' children, which are described as one of the couple's other top priorities in addition to their farming and religion.
"Those kids were everything to them. That's what they revolved their lives around," Taylor said.
The kids are now in the care of extended family, which Doyle got a sense of when she visited the family home after learning about the crash.
She said, "There's a very strong sense of family, community, and they're trying to make sense of what happened."
But it's the not knowing what caused the crash that's adding to the pain, the women expressed. They said they hope people remember the couple not by the way they died, but by how they lived.
"(They were) just one of those perfect couples. Everyone just wishes they had a couple like that. They've touched a lot of lives," Taylor said.
More answers could surface if a crash data recorder can be recovered from the couple's Chevrolet Impala.
Kimmerling said the recorder typically documents the conditions of the car at the time of a crash, but it's unclear if one can be recovered from the Kaeb's vehicle due to the extent of the damage.
Meanwhile, services are Thursday and Friday at the Forrest Apostolic Christian Church, which is where friends say you can also make donations.