Police search lake for missing Kansas City baby Lisa Irwin

(CBS/AP) KANSAS CITY, Mo. - Kansas City police have finished searching a small lake near the home where 10-month-old Lisa Irwin was reported missing over three weeks ago.

Pictures: Missing Kansas City infant

Police said the search Thursday at Chaumiere Lake was not prompted by a tip but was another area near the child's home that needed to be searched.

Police spokesman Darin Snapp says the search lasted only about an hour and nothing of significance was found.

Deborah Bradley and Jeremy Irwin reported their daughter, Lisa Irwin, missing Oct. 4. Police have conducted several searches and fielded many tips but say they have no suspects in the case.

The parents' lawyer postponed a scheduled news conference earlier Thursday, saying the family and people working on their behalf are "exhausted."

Police plan to interview Lisa Irwin's two older brothers Friday with help from a specially trained social worker.

Complete Coverage of Lisa Irwin on Crimesider