While executing a search warrant at the home of Pedro Hernandez, 51, who confessed to killing the boy, New York City detectives found children's clothing and an old toy, the New York Post reported.
An unnamed detective told the Post the items found were "age appropriate" for Etan.
The detective did not say what the clothes or toy looked like, but they appear to be from the late 1970s, when Etan disappeared.
The sources said Hernandez also has a son, so the items would be tested to see if they belonged to him.
Etan was 6 when he disappeared May 25, 1979, as he walked from his home to a bus stop.
On May 24, Hernandez confessed to killing the boy and told police he lured Etan into the bodega where he worked with a soda, then killed him in the basement. He said he dumped the body in an alley nearby.
Since his arrest, Hernandez has been under psychiatric evaluation at Bellevue Hospital because he has a history of mental illness, the Post said.