Police found the bodies of Phuong Hung Le, 30, his wife, Trish Dawn Lam, 25, and Lam's 6-year-old son, Tommy, on Monday when they conducted a welfare check at the family's home on a street lined with two-story stucco houses about 35 miles southeast of Los Angeles in Orange County.
Because of the girl's dehydrated state, detectives believe the killings may have happened Friday night, the last time the family was heard from. She was taken to a hospital for treatment and placed in protective custody. She was not immediately identified.
"It's one of the most horrific crimes that we have investigated in many years," police Lt. Dennis Ellsworth said.
He said there were no signs of forced entry, suggesting the couple might have known their attacker. "It looks like they took some time in the house, it wasn't like they went in and left right away," Ellsworth said.
Investigators did not know the motive for the attack, and no arrests had been made. They ruled out a murder-suicide.
Police would not say whether a security camera nestled on the eaves recorded anything or even if it was functional.
People left flowers, a teddy bear and burning incense sticks near the crime scene in a cul-de-sac lined with new tract homes Wednesday.
Among those who came by was Huong Nguyen of Westminster, who said she was a friend of the slain woman.
Nguyen, speaking in Vietnamese, said she last spoke to Lam on Friday night and wondered why there had been no communication over the Memorial Day weekend until she learned of the crime in a newscast. She had expected Lam to come by with her children.
Nguyen said that during visits Lam told her that she loved her husband but that he gambled.
"I really love her because she reminds me of my daughter," said Nguyen, her eyes teary.
Lam's older brother, Philip, said his family was struggling to understand how the killings could happen.
"I'm trying to figure this all out," Philip Lam said in a telephone interview from the family home in Escondido. "So far there are a lot of broken hearts around here."
Philip Lam said the family emigrated from Vietnam a decade ago, and that his sister was the kind of person who was always willing to help out.
According to police, Trish Lam worked for a small casino in San Bernardino County and Le was unemployed. Le had a criminal history, but police said they were not sure whether that had any bearing on the case.
State prison records showed a Phong Hung Le was sentenced to four years on a robbery conviction and more than two years for destruction of jail property. The couple, who had been dating for several years, married in 2005, according to Trish Lam's brother.
"I don't know about enemies and I don't know how my brother-in-law was doing. He was always home. He didn't really go out much," Philip Lam said.
As for the baby girl, he said his parents would like to raise her if they can.