Police have visited the couple's apartment numerous times in the past year in response to calls from neighbors, but no arrests had been made, he said.
Officers last visited the apartment on Jan. 29 to conduct a welfare check on the girl, Troendly said. Everything appeared to be all right as police conducted a field sobriety test on the couple and interviewed the girl, he added.
"There was no indication that there would be any danger in that household," Troendly said. "When you hear a case like this, it's shocking and disheartening.
"Our community is being impacted by how this could happen to someone at such a young age. It's mindboggling."
Linda Canan, Napa County's Child Welfare Services director, told KGO-TV Tuesday that while she could not comment specifically about Kayleigh's case, a child has died.
"Everything I know at this point in this point in time tells me there was nothing that was done incorrectly," Canan said. "That doesn't mean the system didn't fail. We have a dead child."
County spokeswoman Elizabeth Emmett said Tuesday that the child welfare services department plans to ask the court on Wednesday for permission to talk publicly about the girl's case.