UPDATED 05/18/11 11:18 p.m.

AURORA, Ill. (WBBM/CBS) — The hunt for a missing 6-year-old Aurora boy has intensified, with involvement now from the feds.

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As WBBM Newsradio 780’s Lisa Fielding reports, it has been a week since Timmothy Pitzen was pulled of his kindergarten class by his mother.

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Now, the FBI and U.S. Marshal’s office have joined in the hunt.

New agents join a specialized missing children team dispatched Monday, which already includes investigators from Illinois, Iowa and Wisconsin. CBS 2’s Kristyn Hartman reports.

The last time anyone saw Timmothy was Friday afternoon. He was with his mother, Amy Fry-Pitzen, at the Kalahari Resort in the Wisconsin Dells.

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Earlier in the day, Fry-Pitzen had pulled her son out of school, and took him to Brookfield Zoo and Key Lime Cove in Gurnee.

Sometime afterward, Fry-Pitzen committed suicide. She was found dead on Saturday in a Rockford motel room after slitting her wrists. Her car has been located, and the family says the fact that Timmothy’s car seat and backpack were not inside may be a positive sign that the boy is with somebody else.

Fry-Pitzen left a note behind indicating that Timmothy was fine, and in the care of unnamed people. Aurora police are talking to friends and relatives of the mother, but since then, there has been no sign of the boy.

Cell phone records show Fry-Pitzen and her son were near Rock Falls or Sterling, in western Illinois, before she shut off her phone.

CBS 2’s Mike Puccinelli reports that credit card receipts also indicate that Amy Fry-Pitzen bought clothes and toys for Timmothy on Thursday, about a day before she committed suicide.

Timmothy 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.

The backpack and his car safety seat are also missing.

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The Sun-Times Media Wire contributed to this report.