The woman, identified as 51-year-old Carmen Montenegro, has been arrested. Investigators were digging for clues in the backyard of a home where the suspect was staying.
The Ontario Police Department received a report at about 3 p.m. Sunday that a female was pushing a trash can down the street near H Street and Holmes Avenue. The caller told police that it looked like there was a body inside the trash can.
Police said officers found Montenegro and the body of a man in the trash can. The body was not identified.
Authorities are calling the incident a homicide, but investigators say they are still trying to determine if the crime was committed at the location where the woman was found or somewhere else.
Nearby resident Christina Sanchez said she witnessed Montenegro being taken into police custody.
"She looked like she was dazed and confused, but you know, I only seen her for a second as we drove by," she said.
Investigators were seen digging in the backyard of the home where the suspect had been living and were interviewing people at the home.
Police say they are interviewing several witnesses.
"There are concerns that we have not found the entire body, concerns us, and that's what we want to continue to develop information on, and to determine where other portions of the evidence is on this case," said Ontario Police Det. Jeff Crittenden
Montenegro has been booked at the West Valley Detention Center on homicide charges.
Anyone with information related to this case should contact the Ontario Police Dept. at (909) 395-2752.