(CBS/KCCI) AURORA, Ill. - Investigators said they are asking geologists to help in the search for missing Illinois 6-year-old Timothy Pitzen, who disappeared after his mother committed suicide at a hotel.
"What were trying to do here is pinpoint an area that we can start searching. We got a huge circle and we really need to make that smaller," said Dan Ferrelli, the spokesperson for the Aurora Police Department, reports CBS affiliate KCCI.
Investigators hope Timothy's mother's SUV might provide an important clue in the search.
The SUV has a lot of dirt and grass on it that police are asking geologists and other specialists to analyze.
"What we think is, if any of the vegetation or dirt is unique to any parts of Illinois, it would be a great place to start searching," said Ferrelli, reports the station.
Until experts analyze the SUV, police have suspended ground searches for the boy.
About three weeks ago Amy Fry-Pitzen, Timothy's mom, killed herself in a Rockford, Ill., hotel and left a note saying Timothy was safe and with people she did not identify.
Police still do not know where the boy is.
"Definitely a lot more questions than answers," said Ferrelli, the station reports.
Aurora police have now released a number of pictures of things like toothpaste and toys Fry-Pitzen bought for him in the days before her death that they haven't been able to find.
Timothy is described as 4-feet-2-inches tall and 70 pounds, with brown hair and brown eyes. He was last seen wearing green shorts and a Spider-Man backpack.
Anyone with information is asked to call Aurora Police at 630-256-5500.