Illinois State Police investigators broke the news that family was dead the way someone might approach ripping off a Band-Aid.
"Your wife and kids are all dead," Sgt. Gary Lawson told him bluntly, perhaps hoping to provoke a response that might offer some clue as to whether Vaughn was the man who shot his family in cold blood as they sat inside their SUV as the sun rose on June 14, 2007.
"No, that's not possible," Vaughn responded. "Why are you saying that? Can you just bring (my wife) in so I can talk to her?"
Vaughn's interview with the state police, captured on videotape, was shown to a jury Monday as his murder trial headed into its second week.
In the tape, he insists neither he nor his wife, Kimberly, 34, would be capable of shooting anyone, let alone their children, Abigayle, 12, Cassandra, 11, and Blake, 8.
"I could never hurt them," Vaughn said. "They're my kids. They're my future."
Vaughn, dressed in the hospital gown he was given after police confiscated his bloody and cut-up clothing while he was treated for gun shot wounds to the wrist and thigh, was transported to Illinois State Police District 5 headquarters in Lockport. He was read his Miranda rights but was not under arrest.
Although Vaughn did ask whether his wife knew where he was at the start of the interview, the early part of the conversation mainly focused on how the family came to be on a frontage road off Interstate 55 near in the early morning hours of June 14, 2007.
He said they were headed to a water park in Springfield when his wife began to feel ill. He pulled off at the nearest exit, and looked for a private area where his wife could be sick if she needed to, he said. The children were asleep in the back seat.
While they waited, he decided to check that the rooftop cargo carrier was secure, he said. When he got back into the car, he noticed his leg was bleeding, "which didn't make a lot of sense to me. ... I just don't know what happened."
But that's not what he told the man who stopped to help him as hobbled down the road in search of help, a point the investigators angrily pointed out after he repeated his story several times. There were too many "gaps" in his account and they wanted more answers, they said.
Vaughn said his wife was "not the type" to shoot anyone but he did admit they were having problems with their relationship, in part because he'd confessed to her that he'd been unfaithful on a December 2006 business trip, when he "went home with a few of the ladies."
That caused a lack of trust, he said, and he guessed his wife also knew he had a penchant for visiting strip clubs on occasion, even though they didn't discuss it.
Also putting stress on the family were the frequent out-of-town trips he had to make for his job as a computer consultant, he said.
In fact, after spending the night of June 13, 2007, arguing with his wife about not spending enough time with the family, Vaughn said he decided he would surprise them with a trip to a water park in Springfield that he recalled having seen once when he was in town.
He set his alarm for 4 a.m., and woke his wife and kids with a plan to be on the road by 5 a.m., he told investigators. The day after that, he planned a trip for just himself and his wife to Herman, Mo., to commemorate their "lucky 13" wedding anniversary.
Investigators also broached the possible frustration he may have had with his wife, who had just completed her college degree -- which cost nearly $100,000, Vaughn said -- but didn't seem inclined to look for a job using it. Instead, she got a part-time position at their subdivision's clubhouse.
Vaughn insisted he didn't mind that his wife wanted to continue to stay with the children, but that he wanted her to plan ahead for when the kids would not need her as much. He also cited his wife's sister, who was "perpertually in school," getting degree after degree.
However, the cost of the degree was not an issue because they could afford it. His salary, he said, was $180,000 a year with a $30,000 bonus.
He was trying to improve his relationship with his wife, he insisted.
"I've been working real hard to patch it up," he said. "I was trying to do what she wanted."
Here are the stories from the previous days of testimony: