Christopher Vaughn portrayed himself a family man, but the first investigators looking into the roadside shooting deaths of his wife and three young children immediately had their doubts.
"One of the first things that struck me when I was going through the initial questions is that he didn't -- he couldn't recall his children's birthdays," recalled Illinois State Police Sgt. Gary Lawson.
Kimberly Vaughn was found with a gunshot wound under her chin. The children -- Abigayle, 12, Cassandra, 11, and Blake, 8, -- were each found buckled in their seats with a single gunshot to their chests and their foreheads, prosecutors said.
A Will County jury in September took less than an hour to find the former computer specialist guilty of a crime Lawson described as "one of the most horrific" he'd seen in his career.
The 37-year-old Vaughn was found by a passing motorist, and after being treated at a hospital for minor gunshot wounds, was interviewed by Lawson and Special Agent Cornelious Monroe.
"Mr. Vaughn was very poised, very stiff, spoke very soft," Monroe recalled. "He was very careful with his answers."
Careful, and emotionally detached.
Lawson said that when the pair informed Vaughn that his family members were all dead, he replied simply: "No, they're not."
"There was no elevation in his voice. There was no lean forward. There was no slump-down in disbelief," Lawson explained. "There was almost no reaction because I think he already knew."
When paramedics tended to Vaughn's wounds, Lawson and Monroe watched through a one-way mirror. Vaughn, they said, was joking with the paramedics.
Still, Lawson said he wasn't completely convinced Vaughn was the trigger man. The lack of emotion told the investigators they had to question him another way.
Monroe and Lawson presented to Vaughn large school photos of the now-slain children.
"I took the pictures and I put them together, and I put them up to his chest," Lawson recalled. "I said, 'Hold them,' because he wanted to take them down. And I said, 'No, put them back. Hold them.'"
Eventually, Vaughn became agitated and at one point tore up the photos, a move that drew an emotional response from Monroe.
"I told you not to touch my pictures!" he recalled saying.
Monroe said he later apologized to his boss, Illinois State Police Director Hiram Grau, for the outburst. Grau said the apology wasn't needed.
"You have to do what you think is right to solve the case," he said.
Vaughn was arrested nine days after his family was slain and just hours before his family members were laid to rest.
"When I entered the room to speak with Mr. Vaughn, he asked me, 'Why didn't you allow me to bury my children?" Lawton recalled. "And then I informed him, 'Because you killed your family, that's why.'"