Updated

A man whose wife and three children were found shot to death in the family's sport utility vehicle spent hours talking to authorities after the discovery but police said he was not under arrest and not a suspect in the slayings.

The bodies of Kimberly Ellen Vaughn, 34, and her children — Abigayle Elizabeth, 12, Cassandra Ellen, 11, and Blake Philip, 8 — were discovered around 5:25 a.m. Thursday. They were found in the family's SUV parked on a service road near Interstate 55 in Channahon after a passer-by called 911, authorities said.

The mother was shot once and the children all were shot multiple times, Coroner Patrick O'Neil said.

Kimberly Vaughn's husband, Christopher Vaughn, who had a gunshot wound to the thigh, was with the caller until police arrived, Illinois State Police Capt. Carl Dobrich said.

Christopher Vaughn, 32, was treated at a nearby hospital before being released to police.

Vaughn left the Illinois State Police District 5 offices early Friday, Illinois State Police Master Sgt. Cheryl Lisy said. She said he was never in custody and left "of his own free will." She said she did not have information about investigators' interviews with him.

The family left their Oswego home before dawn Thursday on a "social trip," Dobrich said, but added he didn't know their intended destination.

Dobrich said police did not think anybody else was involved in the shootings. Police in Channahon, about 40 miles southwest of Chicago in Will County, found the SUV on a service road to a cell phone tower just west of Interstate 55 and east of the Heritage Bluffs golf course. A handgun was found at the scene, Dobrich said.

"This event we believe is concentrated to what we have at the scene ... we are just trying to get down to the truth as to what actually happened," he said.

Kimberly Vaughn's sister, Nikki Isemann, told the Chicago Tribune that her sister was looking forward to a romantic getaway this weekend with her husband.

"Kim was very excited about it, getting last-minute things packed," she said. "Her husband, he adored her. He would do everything for her."

Christopher Vaughn's mother, Gail Vaughn, told the Chicago Sun-Times that her son didn't appear to have any marital problems.

"They're a fantastic family," she said. "They really work together."

A neighbor of the Vaughns' spacious Oswego home, about 20 miles north of Channahon, said he had never seen any signs of discord at the Vaughn household, where he said police detectives were working most of Thursday.

"They were very nice people, both the wife and husband ... they looked like a loving couple," said Mohammad Ansar. "They were like a perfect family if you saw them."

The mother would walk the kids to a school bus in the morning, said Ansar, adding that the three children "were very cute" and "very well behaved."

Ansar described Kimberly Vaughn as "a homemaker" who got a degree online last year. Another neighbor, Tony Bridges, told the Tribune it was a criminal justice degree. Christopher Vaughn works as a computer forensic adviser, his mother said.

An article last month about the Vaughns' Oswego home in the real estate section of the Sun-Times featured an idyllic photo of a relaxed Christopher and Kimberly Vaughn sitting at a dining table — their three children standing behind them smiling.

"We really liked the small-town atmosphere of Oswego," Kimberly Vaughn told the Sun-Times. "We also checked on the schools our three children would be attending and found them to be highly rated."

The Vaughn family moved from Washington state to the Chicago area about a year ago, bringing their two dogs with them, according to the May 27 article. They lived briefly in an Aurora apartment before relocating to the 3,373-square-foot, 4-bedroom home in an Oswego development where home prices started in the low $300,000s, the article said.

A police chaplain and counselors were available for police who responded to the scene of the shootings, Dobrich told reporters Thursday.

"To be blunt, I have kids at home that age," he said. "And it affected people there immensely. It was a very sad scene."