Law enforcement officials consider Ricardo Alekzander Lara to be in "grave danger."
Police were seeking the boy's biological father, 23-year-old Ricardo Lara Martinez, in connection with his disappearance. Martinez was said to be a "person of interest" in the death of Maria Isabel Romero Medina, 27.
Denton police said Sunday that someone reported seeing the child and his father at a Houston convenience store. Martinez also is said to have ties to Chicago, Springfield, Mo., and Mexico City.
Detectives also were checking another lead, but would not elaborate.
Police said they were called to the Sanchez Insurance and Tax office in Denton, Texas, Saturday evening after a customer found the door locked. Another employee of the business entered to find Medina inside. Denton, a city with an estimated population of 123,099, is nearly 40 miles north of Dallas.
Martinez is described as a Hispanic male with brown hair and brown eyes. He is 5 feet, 5 inches tall and weighs 150 pounds. Police did not say what he was wearing, and no vehicle information was available.
The child is 3 feet tall and weighs 55 pounds and has brown hair and brown eyes. He may have been wearing a blue shirt and shorts.
