"You will go to jail, and whoever has been helping you, if they don't talk, they will go to jail," Desiree Young, Kyron's birth mother, said today in an interview with Andrea Canning on "Good Morning America."
"I really believe that you want to do the right thing here and bring Kyron home," she said.
Terri Horman, the last known person to see Kyron when he left her to go to class at his elementary school following an early morning science fair, has come under increasing suspicion.
Kyron's father, Kaine Horman, has since filed for divorce, after being told that she had allegedly tried to hire someone to kill him. Police have not called Terri Horman a suspect, but have indicated that there are discrepancies in her account of what happened on the morning of June 4.
Terri Horman has remained steadfastly silent through most of the investigation, only releasing brief statements through her attorney that she did not have anything to do with Kyron's disappearance.
"I'm extremely angry," Young said. "I don't even know if I can communicate how angry I am."
This week Terri Horman made a rare appearance during divorce proceedings, but she reportedly has refused to cooperate with police investigating her stepson's disappearance.
Police recently released photographs of Terri Horman's white truck, asking for help identifying a person seen in or around the vehicle the morning Kyron vanished.
Young said she and Kaine Horman believe that the person police were asking about was Terri Horman's friend, DeDe Spicher, who was reportedly unaccounted for the morning of June 4.
Spicher has told People magazine that she working that day and that she continues to support Terri Horman.
Young said today that she feels Terri Horman and Spicher should come clean with police.
"If they are innocent then they both need to talk and clear themselves," she said.
Terri Horman's lawyer, Stephen Houze, has said that his client has been receiving death threats and that the media frenzy surrounding the case has morphed into a "witch hunt."
Kaine Horman said today that the alleged murder plot against him made him think his estranged wife might have done something with her stepson as another way to hurt him.
"We've all seen the murder for hire plot surface, so obviously there was a problem so that didn't work out and she resulted to other things," he said on "GMA."
Kyron was last seen walking toward his Skyline Elementary School classroom after he had proudly displayed his science fair project on tree frogs.
He was last seen wearing a "CSI" T-shirt and black cargo pants.
With Kyron's eighth birthday just days away, Kaine Horman and Desiree Young said they will have the present he asked for just before he vanished -- a remote-controlled boat -- waiting for him when he comes home.
"How loved is this little boy? Oh gosh. More so now than he ever was because he has tons of people in the world rooting for him," Desiree said. "You can't look at Kyron, that little smile, and think anything bad. He never chose this."