The suspect, identified as Isabel Diaz Castillo, 30, was taken into custody Wednesday -- about four hours after the boy, Carlos Orozco was found, the St. Paul (Minn.) Pioneer Press reported.
At about 11:55 a.m. Wednesday, Carlos' mother placed the boy in a car seat inside her apartment so she could take a shower. When she came out of her shower, the boy was gone.
Police said they received an anonymous tip that led them to a relative of Castillo's home, where Castillo and Carlos were found.
Minneapolis Police spokesman Sgt. William Palmer said he could not yet say what the motive behind the kidnapping was, but added that Castillo "had been paying an inordinate amount of attention to the child" over the past few weeks after she befriended Carlos' mother.
Carlos was reunited with his mother after paramedics checked him out and determined he was unhurt.