Trying to figure out what set off a 41-year-old father, homicide investigators Monday interviewed the lone survivor of a weekend murder-suicide and searched the Yorba Linda home where five family members were killed.
Brea Police Lt. Jack Conklin said the new search was prompted by the detectives' hospital interview with Ian Mercado, 14, but the officer declined to say what police were seeking. The teenager is in stable condition at a hospital, recuperating from a gunshot wound to the lower torso and a hand.
"Ian holds the key to a lot of what happened," Conklin said. "We're hoping he can fill in some of the blanks. There's lots of them."
Ian's mother, Maricel Cho, 39; sisters Nicole, 9, and Kathleen, 8; and brother Christopher, 5, were killed by Orland Cho on Saturday night. Cho turned the shotgun on himself after shooting his family, police said. Ian is Maricel Cho's son from a previous relationship.
Detectives were struggling to find a motive for the shootings and to piece together information about the gunman to help them understand who he was. There were still many unanswered questions, including where he worked, Conklin said.
Interviews with other family members have proved inconclusive in establishing a motive, he added.
Police believe Maricel Cho was a nurse.
A spokesman for the Orange County Department of Child Support Services said the Chos separated in early 2004, and Maricel Cho applied for welfare assistance.
While investigating her application, authorities determined that Orland Cho was able to pay child support, and the agency sued him. In 2005 the couple reunited, and Maricel Cho asked the county to close the case. Orland Cho agreed to pay back the payments the county had made to his family. The spokesman did not know the total amount.
Killings are rare in Yorba Linda, a quiet community spread out across foothills and crisscrossed with equestrian trails. The murder-suicide occurred across the street from the Richard Nixon Library & Birthplace.
On Monday evening, Placentia-Yorba Linda Unified School District officials were scheduled to hold a community meeting at the district's education center where parents were going to be instructed on how to speak to their children about grief. Police, clergy and counselors would be available to answer questions.
District spokeswoman Rosemary Gladden said students at Mabel Paine Elementary School remembered Nicole, Kathleen and Christopher on Monday as they tried to understand their deaths.
Nicole, a fourth-grader, had excelled in every subject but was especially strong in math. Her classmates recalled that she was quiet, polite and liked to play handball, Gladden said. She also played the cello and performed at a school concert last week, days before her death.
Kathleen was a third-grader who excelled in art. Her classmates remembered her fine penmanship and sense of humor, Gladden said. She was a straight-A student and shy.
Christopher, a kindergartner, had just learned to read and had recently received a certificate for good behavior.
Ian, an eighth-grader at Yorba Linda Middle School, is a good student with many friends, Gladden said.
The shootings occurred about 11 p.m. Saturday. A neighbor called emergency services to report gunshots, and Ian called about two minutes later.