San Bernardino County coroner's officials will determine if the remains - including bone fragments and teeth - are from the body of Oscar Javier Contreras Escobar of Laguna Hills.
Ontario police announced Tuesday that they had completed their search at a residence in the 1700 block of South Palm Avenue.
"We need to conduct further forensic analysis to determine if this is Escobar's remains," police Sgt. David McBride said.
Escobar, 29, was reported missing in September to the Orange County Sheriff's Department.
The self-employed truck driver was last seen Aug. 28, when a friend dropped him off near Mango Avenue and Foothill Boulevard in Fontana.
Orange County sheriff's officials took the missing-person report, but Ontario police detectives took over the investigation in November.
Three people - two men and a woman - were at the home last Wednesday when officers began the search, officials said.
Officers interviewed and released all of them.
Police were treating this as a homicide investigation but had not made any arrests.
Officers have also looked into several leads, including suspicious activity on Escobar's ATM card.
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