The fire had been labeled suspicious, and on Thursday authorities confirmed the four had been killed before the fire was set. Sheriff's homicide detectives are investigating.
"We believe the burns did not contribute to the death, that they were killed prior," Los Angeles County coroner's spokesman Ed Winter said.
Authorities did not release the names of the other three victims but said they were relatives of Ciganek's wife. The woman and the older child, a girl of about 13, were stabbed to death, Winter said. Ciganek and the other child, a boy of about 10, were beaten and slashed.
Neighbors said Ciganek, 60, and his wife had lived in the house for at least 13 years.
Ciganek worked at NASA's Dryden Flight Research Center at Edwards Air Force Base, a NASA spokesman said.
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