The Reedley, California Police Department said a 17-year-old boy has been arrested on four counts of homicide.
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Officials say the teen's mother, 34-year-old Brynn Curtis, and her boyfriend, 21-year-old Rafael Gonzalez, have also been arrested on charges of accessory after the fact.
The arrests come after investigators say 81-year-old Billy Bonds, 44-year-old Guadalupe Bonds, and a third person were found dead at a home on Saturday morning.
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On Tuesday, police found a fourth body during a search of the home next-door to where the three victims were found.
Officers also served search warrants at a Parlier, California home and another house in Selma, California, where they impounded two vehicles.
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Police have been searching for Matthew Bonds, who is Guadalupe Bonds' husband.
They have not yet confirmed if the body found Tuesday morning could be his.