Kristin Smith is not considered a person of interest in the missing baby case, Beloit Police Chief Steve Kopp said.
Kayden J. Powell, was discovered missing early Thursday morning. Kopp said his parents, Brianna Marshall and Bruce Powell were "exhausted" and "distraught," the Daily News said.
The Beloit Daily News reported Smith was visiting the baby's home Wednesday evening, but left early Thursday for her home in Colorado. After the baby was reported missing, police contacted Smith on her cellphone and she told them she was in Iowa, the report said.
She pulled off the interstate and met West Branch, Iowa, police, who learned of an outstanding warrant in Texas against her, the Daily News said.
Kopp said he would hold a news conference Thursday afternoon but did not set a time.
The Rock County Sheriff's Office and the FBI Division of Criminal Investigation have joined the case.