The couple had failed to pick up their three children from school Wednesday, prompting the officers' visit.
Yulianna Nikulina, who lives next door, told the Pilot that earlier in the week, around 6:30 a.m. or 7 a.m. Monday or Tuesday, she heard Quee Chadwick scream.
Nikulina said she thought maybe it was an expression of momentary frustration, possibly while getting the children ready for school. Nikulina said he family is normally quiet and polite and she never heard fighting or yelling coming from the home.
"Peter [was] always nice, nothing wrong, nothing special," she said. "I can only tell you good things about this couple."
She and other neighbors were questioned by police.
Nikulina said the Chadwicks have three boys, age 8, 10 and 14, each well-mannered.
Peter Chadwick worked from home in real estate, Nikulina said, and Quee was a stay-at-home mother who came to the U.S. from China.
Public records show businesses Chadwick Pacific, Great Glove USA Inc. and Chadwick California LP linked to the home on Almanzora. Great Glove USA lists Quee Chadwick as its president, and a LinkedIn profile for Peter Chadwick names him as an investor and president of Chadwick Pacific.
All was quiet Friday at the palatial yellow home with small green tile accents on Almanzora.
But when officers entered the home Wednesday, they saw "evidence of a struggle and possible foul play," police said.
Concerned the struggle may have been fatal, police immediately launched a search for the Chadwicks.
Peter Chadwick called San Diego police about 5:30 a.m. Thursday, requesting help from a location near the border, police said.
Police would not say what Chadwick told them, but they said that their investigation determined Quee Chadwick was the victim of a homicide.
However, they have not found the victim's body. Newport Beach police are conducting a widespread search of the areas they believe Chadwick traveled during the 12-hour period before he contacted San Diego police.
Police said the couple's children were in good care but did not elaborate.
—Los Angeles Times Staff Writer Richard Winton contributed to this report.