Suburban Chicago authorities searching for a 6-year-old boy say that at least one of the steps his mother took before she committed suicide that suggested the boy was safe did not happen.

Earlier this week, authorities said that after they found the body of Amy Fry-Pitzen in a Rockford hotel May 15, they discovered Timmothy Pitzen's car seat was not in the car, leading them to believe Fry-Pitzen may have left the car seat with whomever she left her son. But Saturday, Aurora Police Chief Gregory Thomas said in a news release that the boy's grandmother had taken the car seat a week earlier.

Fry-Pitzen reportedly left behind a note before she committed suicide, saying Timmothy is "okay" and with people who care about him. But did not name the individuals. 

Thomas said authorities are growing increasingly concerned about the boy, who was last seen more than a week ago when Fry-Pitzen took him out of school. 

The FBI and U.S. Marshals service are assisting the search in three states -- Illinois, Ohio and Wisconsin -- for any trace of the child. 

The boy's grandmother said in an interview with Fox 8 that she believes Timmothy is still alive.

"We believe he's alive. We believe that she told someone to watch him and that she would be back," she told the station.

Timmothy, who lives in Aurora, Ill., with his parents, is described as 4-foot-2 and 70 pounds. He has brown hair and brown eyes and was last seen wearing green shorts and a Spider-Man backpack.

Anyone with information on his whereabouts is being urged to call the Aurora Police Department at (630) 256-5500.

Click here for more on the disappearance of Timmothy Pitzen from Fox8.com

The Associated Press contributed to this report