OUTSIDE CHICAGO, IL -- Detectives trying to unravel the mystery surrounding a local woman who vanished nearly a month ago now are also trying to track down her youngest child.

"There's some question as to his whereabouts," Joliet police Cmdr. Brian Benton said of Linda Fellenbaum's toddler son Jonathan.

Fellenbaum, 33, of Joliet, was last seen Oct. 21. At the time of her disappearance, she was living with her boyfriend of two months, 40-year-old Donald Wolak. Benton said Wolak told detectives he and Fellenbaum argued and she fled his 3608 Crockett Court home barefoot, leaving behind her shoes, cell phone and Toyota Camry.

Fellenbaum has not been seen since. But her 2-year-old-son Jonathan has apparently been missing for even longer.

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Fellenbaum's mother, Deborah Barr of Chicago, said in the wake of her daughter's disappearance that Jonathan was staying "for the summer" with a couple Fellenbaum knew from her church. But on Tuesday, Benton said Fellenbaum's family has not been able to identify this couple, and that they have not actually seen Jonathan in months.

"We've had two different stories on them," Barr said of the couple from the Chicago church. One story makes the couple out to be members of the church, the other has Fellenbaum bringing them in from outside to be Jonathan's godparents.

"Linda knows who they are," Barr said. "I don't know who they are.

"We can't find them," Barr said. "We don't even have a picture of them."

Fellenbaum had spoken to relatives about putting the boy up for adoption, but Benton said there is no evidence of a legal adoption having taken place. Detectives have also found no indication that the boy's paternity has been established, he said.

"The father was also Linda's secret," Barr said.

Fellenbaum has two other children. One lives with his father in Country Club Hills and the other lives in Milwaukee.

Whoever Jonathan's father might be, he has not reached out to the police to find out who has his son, Benton said. In fact, he said, no one has filed a missing person report and even though the Joliet police may not have jurisdiction to investigate Jonathan's disappearance, it seems no other agency has taken on the task.

Detectives have contacted the Illinois Department of Children and Family Services about the missing boy, Benton said.

"Right now, we don't have any assurance a crime has been committed," Benton said. But detectives have given no indication they believe Fellenbaum was the victim of foul play either.

Five days before Fellenbaum vanished, Wolak told the police she stole a "large sum of cash" and a handgun from him, Benton said. When she returned on the night she ended up running off barefoot, Wolak said he expected her to return his gun and money, according to police.

Earlier that day, a Chicago man claims to have met with Fellenbaum for a sex date at a Naperville hotel. The man, who asked not to be identified, said Fellenbaum backed out of the liaison at the last minute.

"We briefly saw each other and she got cold feet," he said, adding, "We never ended up doing anything."

Wolak has failed to respond to numerous attempts to discuss his missing girlfriend. Benton said he has cooperated with detectives.