Jackee Raquel Contreras, the boy's mother, and her twin sister Jennifer Rachel Contreras were charged with the murder of 6-year-old Duke Flores Monday as authorities began searching a Victorville landfill for his body the same day. The search continued Tuesday as volunteers went through nearly 600 tons of trash to locate the body.
Detectives believe the boy's body was placed in a dumpster.
MORE: Mother, aunt charged in Apple Valley boy's murder as detectives search landfill
The San Bernardino County District Attorney's Office announced it had filed a single count of murder against each of the sisters.
Flores was reported missing from Apple Valley last week.
The investigation into the missing boy with autism began about 10 p.m. last Thursday when Flores' grandmother requested a welfare check on him, authorities said. Deputies responded to a home in the 22000 block of Cherokee Avenue, where the boy's mother said he had not been seen in over a week.
The sisters are being held on $1,000,000 bail and are next scheduled to appear in court May 13.