Autopsies found no injuries from anything other than fire on the three people killed by a suspicious blaze Friday at their Woodbury house, police said Monday.
Investigators said it could be several weeks before they determine who set the fire and why.
Chao Yang, 38, and his 8-year-old daughter, Holly Yang, died Saturday, after being rescued from the fire and taken to Regions Hospital in St. Paul. Chao Yang's wife, 45-year-old Nancy Her Yang, died Friday.
All died of smoke or soot inhalation and burns, said Deputy Chief Todd Johnson of the Woodbury Public Safety Department.
Investigators are still piecing together what happened in the Silverwood Road house before the fire, which was reported at 3:15 a.m. from a neighbor's home by the sole survivor, 12-year-old Khoua Yang.
The boy was burned on his legs and was listed Monday in serious condition at Regions.
Police did not identify a suspect Monday, but investigators say they think one of the four people in the home started the fire. There were no signs of an intruder or forced entry.
Officers have interviewed Khoua Yang but have not learned anything that narrowed the investigation, said Kevin Smith, spokesman for the Minnesota Department of Public Safety. Officers also have interviewed members of the Yangs' extended family to "see what might have happened to lead up to this event," Smith said.
"We're trying to figure out what happened," Johnson said. "It could be about any range of scenario that you can imagine. We haven't focused on any one (theory) yet."
"The answer lies with the family members inside the house," he said.
Rescuers arrived at the house about two minutes after the fire was reported. The two adults were found lying unconscious near a staircase on the split-level home's lowest level. Holly Yang was in a bathtub in an upstairs bathroom.
"We knew where the people were, but how they ended up in those positions is still unknown," Smith said. "This is a strange one because of the circumstances; we can't deduce anything until the facts tell us what happened."
An accelerant similar to gasoline was found on all three levels of the home, Johnson said. Johnson said it could take several weeks for lab results to determine its chemical makeup.
Whether the case then would be sent to the Washington County attorney's office for review depends on who is identified as the suspect, said Sue Harris, first assistant county attorney.
"It's really a mystery," Harris said.
Chao Yang worked as a biochemist at DiaSorin Inc., a Stillwater company that makes medical test kits. Nancy Yang worked part time in the deli at Kowalski's Market in Woodbury.
The couple bought their home in January 2004, and police and fire crews had never been called there before Friday.
Chao Yang's brother, Kee Yang, said he spoke briefly with Khoua Yang on Monday.
"He's pretty tired, and I didn't want to bother him," Kee Yang said.
Kee Yang said he did not want to speculate about the cause of the fire.
"I'm concentrating on how much I've lost," he said. "I'm going through a very emotionally stressful time right now, and I'm going to leave (speculation) to the investigators."
Khoua Yang is a seventh-grader at Woodbury Junior High School; Holly Yang was a third-grader at Woodbury Elementary.
A crisis team of social workers, nurses, counselors and a psychologist was available Monday to talk with students and staff, said Barb Brown, director of communications for the South Washington County School District.
The family belonged to the Church of St. Vincent de Paul in St. Paul. Chao Yang and both children were active in religious education there, said the Rev. Joseph Johnson, their priest.
"I found them to be a lovely family, and we're all very saddened by this loss and puzzled at the same time," Johnson said.
Johnson visited Khoua Yang on Monday and said the boy's condition is improving. He also spent time Monday helping establish a trust fund for the boy.
"We need to support him with all the prayers and love and material help that we can muster, because this very bright little boy is going to have a very tough path ahead of him," he said.
Mary Divine covers Washington County. She can be reached at 651-228-5443.
Nancy Yang's funeral will be Oct. 23 and her burial will be Oct. 24. Funeral arrangements are still pending for Chao and Holly Yang; Metro Funeral Home in St. Paul is in charge of funeral arrangements.
A trust fund is being set up to help Khoua Yang through the Yang family's church, the Church of St. Vincent de Paul. Checks may be sent to the Khoua Yang Fund, c/o Premier Bank, 2866 White Bear Ave., Maplewood, MN 55109.
Distributed by the Associated Press
