They could have just kept going, but they didn't.
It was another cold South Dakota day on Feb. 28, 1981, when Lee Litz went out with a friend to test-drive a Jeep.
They picked up another friend on the southeast side of Sioux Falls and drove out a ditch-lined road through barren cornfields.
Litz was 30 and married with four children. His wife, who was pregnant, was back at home confined to bed -- a precaution taken to make sure she could bring their unborn child to term.
As Litz and his friends approached Sycamore Avenue, he noticed a blanket lying in a roadside ditch.
"I got curious," he told me in an interview this week. "It looked out of place."
"We were going to leave," he said. But he told his friend, who was driving, to stop.
"I got out of the vehicle and went over and lifted the blanket up and there he was," Litz said. "He was laying on his side with his back to me."
"The guys that were there with me said I jumped about straight up in the air and I ran over to the vehicle and said we got to call the police," he said. "There's a dead baby in the ditch."
"We didn't have cellphones back then," Litz said, "so we ran over to my one friend's house, which was about a mile away, and called the police from there."
"They came out and picked me up and took me out to the scene," he said. "I was hoping that I had found a doll or something like that. I was just praying that it wasn't really a baby. But it turned out to be that wasn't the case. It was a baby."
A police affidavit later described the horrendous scene Litz had discovered.
"The newborn had the placenta still attached, and laying next to the baby was a pair of women's panties, a shirt, and Kleenex type material all with blood on them," it said.
The local coroner's office determined the baby had been born alive and, according to the affidavit, "the cause of death was most likely exposure and failure to assist the baby in maintaining an airway."
People in Sioux Falls reacted with horror and compassion. The little boy was named Andrew John Doe, given a public funeral and buried in a plot donated by St. Michael, the local Catholic cemetery.
The Sioux Falls Police investigated aggressively but found no solid leads. The case went cold.
But baby Andrew was not forgotten.
In 2009, Detective Mike Webb reopened the case, believing DNA evidence might solve it. Baby Andrew's body was exhumed and sent to a lab at North Texas University. The university developed a DNA profile of the boy, and his body was returned to St. Michael Cemetery.
The Sioux Falls Police then checked baby Andrew's DNA against the South Dakota DNA database. There were no matches.
They periodically repeated this check for eight more years. Nothing.
Then, last year, the Sioux Falls Police gave a sample of baby Andrew's DNA to Parabon NanoLabs, a company that helps police link DNA from crime scenes to genealogical information. Parabon, according to the affidavit, "found two possible genetic familial matches."
Sioux Falls Police Detective Patrick Mertes then used "public domain research websites" to build a family tree that might lead to the person who left baby Andrew in the ditch.
The key suspect still lived in Sioux Falls.
Detective Mertes carried out what police call a "trash pull" -- taking items from the garbage she had thrown away.
DNA recovered from items in this garbage belonged to a woman and a man who "could not be excluded" as being the biological mother and father of baby Andrew.
The police then took direct DNA samples from them. These proved they were Andrew's parents.
The woman's name is Theresa Bentaas. She was 19 years old in 1981.
On Feb. 27, 2019, 38 years after baby Andrew was born, Detective Webb went to her house to talk to her.
"The defendant admitted being pregnant in 1980-1981 and hid the pregnancy from her family and friends," said the police affidavit. "The defendant stated she had the child in the apartment alone, then drove the baby to the place where he was later discovered."
"When asked what she was thinking when she drove away from that ditch she stated that she was sad, scared, and she ran from it and it was not smart," the affidavit said.
She did not marry the man who was Andrew's father until six years after she left the baby by the side of a road.
He told the police he "did not believe the defendant was capable of doing such an act," and they determined he was unaware of the crime.
On Friday, Theresa Bentaas was charged with murder and manslaughter. No charges were brought against her husband.
That day, Lee Litz got a call from his daughter, Crystal Oestreich, who was born three months after Litz found Andrew in the ditch. She told him the suspect had been charged.
"I cried," Litz said. "I couldn't believe it. I was so happy."
What is the lesson here?
"I guess my message would be if you have a baby and you don't want to keep him, take him to a fire station or a hospital or somewhere and drop him off," said Litz. Do "not to have a baby and dump him in the ditch like garbage."
And America could learn this from Sioux Falls: Never stop fighting to defend innocent life.