Update: Police in Gastonia, North Carolina, believe that they have found the body of Maddox Ritch.
"It didn't look as though they were that concerned," said Rick Foxx, who works at Rankin Lake Park in North Carolina, of the boy's father, Ian Ritch, and his girlfriend, according to CBS News. "I've worked there almost three years and we see everybody come in and out of that park pretty much. I didn't see that kid one time."
On Wednesday, the FBI released the 911 call made by Foxx, an hour after Ritch says Maddox disappeared. He approached Foxx at the park for help. In the call, Foxx tells the 911 operator that Maddox was last seen by a pier and some trees in the park.
Maddox is autistic and nonverbal, according to authorities.
Ritch joined Gastonia, North Carolina police and FBI agents for a news conference Wednesday, hours after appearing on ABC's "Good Morning America" to talk about his son.
"I just want my little boy back," Ritch said. "It's been torture. I'm not eating, not sleeping. I'm just worried about getting my little boy back."
Ritch said his son ran a short distance from him before he broke into a sprint after he spotted a jogger. Ritch said Maddox usually runs away, but would either slow down or stop.
Ritch said he is diabetic and because he has neuropathy in his feet, he has trouble running.
"He likes running," Ritch said. "I couldn't catch up with him. I feel guilt for letting him get so far ahead of me before I started running after him."
Ritch said the boy looked back at him and laughed, adding that he would slow down and then speed up again. With the help of his friend, Ritch searched for his son but couldn't find him. Park personnel also joined in the search but didn't see Maddox, either. After an hour, 911 was called.
Gastonia Police Chief Robert Helton said they've searched thousands of acres, drained the lake and conducted hundreds of interviews. Helton said investigators still want to speak to a jogger, a person who was pulling a kayak out of the lake and anyone in a group photographing three children in Dr. Seuss costumes.
Meanwhile, Ritch knows he's a potential target for investigators in his son's disappearance.
"I mean, I know I'm the number one suspect when it starts. That's plain and simple," Ritch told CBS News, adding that he has cooperated with investigators. "Everything that they've asked for, I've given them right off the bat."
Ritch told CBS News he took two polygraph tests. However, the FBI has refused to comment on the results of those tests, according to the outlet.
Foxx expressed cynicism over Ritch’s reaction to his missing son.
“He didn’t act like a concerned parent, like I would act, or any concerned parent would act,” Foxx told WSOC-TV in Charlotte.
Ritch, who has blonde hair and blue eyes, was last seen wearing black shorts and an orange T-shirt that said "I am the man."
The Associated Press contributed to this report.
[Photo: Gastonia Police Department]