Investigators were still working to determine the relationships among the victims, who were found tangled in a pile of clothes when police went to the home about a child custody dispute Friday.
Marcus Wesson, thought to be the father and grandfather of the victims, walked out of the home covered in blood and was booked on suspicion of nine counts of murder.
Authorities said Wesson, 57, may have been involved in polygamy and is thought to have fathered children with at least six women, including two of his own daughters.
In a Friday afternoon press conference, Dyer said Wesson was cooperating with investigators, but no motive had yet been determined.
"In terms of any type of ritual, those are being investigated by our officers. No motives have been ruled out," Dyer told CBS News Correspondent Manuel Gallegus.
Dyer called the slayings one of the worse cases he's ever seen.
"It's just the feeling you get seeing ... people deceased all in close proximity to each other," Dyer told The Fresno Bee.
"Three toddlers and an infant is possibly the most disturbing thing," he said.
Dyer said police had been called to the Wesson home six times in the past three years, but never for reasons relating to children or violence.
Wesson's arraignment was scheduled for Wednesday; bail was set at $9 million.
Authorities expected to release the names of the victims by Friday: a 24-year-old woman and eight children ranging in age from 1 to 17.
Coroner Loralee Cervantes said police conducted tests to determine if there was gunshot residue on the hands of one of the victims, indicating Wesson may have had help with the shootings. Police Lt. Herman Silva said checking for residue is standard practice.
The victims, who had six different mothers, showed no signs of physical or sexual abuse, Cervantes said Monday.
Acquaintances said Wesson and his family appeared to live a nomadic, insular existence. The family moved several times in recent years, from a small boat anchored off Santa Cruz to the mountains outside Watsonville, before settling in Fresno.
In the early 1990s, Wesson lived with a few children on a battered, 26-foot sailboat that had no toilet or bathing facilities.
During that time, he was jailed briefly after being convicted of welfare fraud, the Santa Cruz Sentinel reported. Wesson failed to list his boat as an asset on welfare forms. He also was frequently delinquent with his slip fees, the newspaper said.
Other acquaintances said Wesson appeared with women and children who seemed to be under his control. Frank Muna, a lawyer who once sold the murder suspect a house, said the women wore dark robes and scarves, walked behind Wesson and did not speak when he was present.
Muna said Monday police interviewing him said Wesson killed his children because he didn't want them taken away from him.
"He really thinks what he did was right," Muna said.
Silva, the police spokesman, refused to confirm Muna's account, saying only, "We're looking at every possible motive and not dismissing anything."
The children were home-schooled because Wesson did not trust public education, his sons said, and Wesson, who did not work, was supported by the women.
Dyer said investigators will likely need DNA testing to determine the biological parents of all the victims. "We're in the very early stages of a very complex investigation," he said.
Wesson's sons, Dorian, 29, who lives in Santa Cruz, and Serafino, 19, who lived at the Fresno house, could not say whether he was married or how many children he has fathered, the Fresno Bee reported. They said the family belonged to the Seventh-day Adventist church. A church spokeswoman said Monday there's no record of Wesson's membership.