Patricia Ripley, 45, was arrested in Miami-Dade for Alejandro Ripley's murder.
An Amber Alert that had been issued for Alejandro Ripley was canceled on Friday morning.
The Amber Alert was first issued on Thursday night after Ripley was abducted from his mother's vehicle.
Patricia Ripley, 47, of West Kendall, was booked into the Miami-Dade County jail early Saturday following hours of questioning by police, the Miami Herald reported.
They confirmed the body is that of a young boy.
Police have asked anyone with information about Alejandro's whereabouts after his abduction or who could help identify the alleged kidnappers to contact police as soon as possible.
"The child was abducted by two unknown black males driving an unknown light blue 4-door sedan", the alert said.
Investigators say Alejandro was with his mother as she drove westbound on SW 88th Street.
Ripley, 47, said the driver of the unknown vehicle attempted to side swipe her auto and forced her to turn onto SW 158th Avenue, police said.
Ripley told Miami-Dade police that she and her son were followed and ambushed Thursday night by two men in a vehicle who demanded drugs. She said the suspect snatched her son and her cellphone, according to police, then got back in the auto, which drove away. One of the them was described as possibly wearing all-black clothes and a black bandanna face mask, and might have cornrows. Anyone with information is urged to call 911 immediately.
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