Jeff Dale, a detective with the Mercer County Sheriff's Department in Illinois, said Aimee Hankins, 34, entered the foster home during the night and took her son, Devin K. Hankins.
"We have credible information that Ms. Hankins took her son from the home and is now on the run with him," Dale said.
Hankins has been charged with felony child abduction and her bond has been set at $1 million in Mercer County.
Additional charges by the FBI are expected this week, Dale said.
"Initially we feel like there is a high potential for danger in this situation," Dale said.
Aimee Hankins, her son and a male accomplice are traveling in a gray 1994 Ford Taurus with the license plate number 502GKP, he said. The car is registered to Larry Steven Carlisle of Cherokee Village, according to the America's Most Wanted Web site.
Dale said investigators think Aimee Hankins has friends in the Tri-County area and she may have passed through here on her way to Mountain Home.
"Honestly right now they could be anywhere," Dale said.
America's Most Wanted contacted the Mercer County Sheriff's Department Sept. 3 and issued an all points bulletin to find Devin Hankins, Dale said.
According to Mercer County officials, Devin Hankins was last seen at 10:15 p.m. on Sept. 1. The next morning, Dale said Devin Hankins' foster parents discovered he was missing.
He said the foster parents are the parents of Devin Hankins' 14-year-old stepsister.
"There has been a lengthy ongoing custody battle since Ms. Hankins' son and husband died a couple of years ago," Dale said.
Aimee Hankins' son, 5-year-old Andrew Hankins, died from a form of Batten's disease in September of 2003.
Two days after Andrew died, Aimee Hankins' husband, Loren Hankins, died of cancer, Dale said.
The family was the subject of a feature story in the Villager Journal in July 2003.
Devin Hankins has been in and out of foster homes in Arkansas since his brother's death, he said.
Devin is a white male, standing 4 feet, 8 inches tall and weighs approximately 85 pounds. His hair and eyes are brown and he wears silver rim wire glasses. Devin has a mole on his neck and was wearing a pair of mesh shorts the last time he was seen.
Aimee Hankins is a white female, standing 5 feet tall and weighs 125 pounds. She has brown hair and green eyes and has visible tattoos on her wrist and forearm.
A reward of up to $1,000 will be paid to the for information leading to the recovery of Devin Hankin, Dale said.
Anyone with information about the whereabouts of Devin or Aimee Hankins can contact the Mercer County Sheriff's Department at 800-582-2762 or the Sharp County Sheriff's Department at 870-994-7355.
For more information visit America's Most Wanted's Web site at www.amw.com