The Memorial Day weekend will send crowds of people into the forests and campgrounds of northern Idaho, and law officers on Tuesday asked them to keep an eye out for two abducted children missing for more than a week.

Authorities continue to receive tips, but have not developed any suspects or strong leads in the whereabouts of Dylan Groene, 9, and his sister Shasta, 8, missing from a home where the bodies of three people were found on May 16.

"There will be thousands of people going to national forest lands and BLM lands around the Coeur d'Alene area," Kootenai County Sheriff's Capt. Ben Wolfinger (search) told a news conference. "We ask if anybody camping in those grounds sees anything suspicious, please don't touch it. Contact law enforcement."

An extensive search of the heavily wooded area around the family's home eight miles east of Coeur d'Alene yielded nothing.

"We have to think outside of our general area," Wolfinger said. "National forests are a natural area for disposal of evidence."

The FBI is sending 30 additional employees to the area to help in the search, including experts in child abductions, Wolfinger said. They will join some 40 investigators from various agencies already on the case.

Some 1,000 tips have been phoned in so far, ranging from possible sightings of the children to "I drove by a field that was glowing. I think the children are there," Wolfinger said.

A public memorial service was scheduled Wednesday for Brenda Groene, 40, mother of the missing children, and Slade Groene, 13, their brother. The third person who died in the house, Mark McKenzie, 37, will have a private ceremony. All three were bound and bludgeoned to death.

Police have developed no motive and no suspects for the killings or the disappearances, Wolfinger said. There were no signs of forced entry at the rural house, and officers believe the children were inside the home when the crimes occurred, he said.

Initial toxicology reports showed Brenda Groene and McKenzie had used illicit drugs.

Wolfinger said Monday that the father of the missing children was not a suspect in the case, even though he failed parts of a lie detector test.

Steve Groene (search) told FOX News' Geraldo Rivera he lacked an alibi and failed portions of a voluntary polygraph test administered by the FBI, but Wolfinger said Monday that was not enough to make Groene a suspect.

"There is no evidence linking Steve Groene to this crime, to make him a suspect or a person of interest," Wolfinger said. He attributed the polygraph results to Groene's emotional distress over the slayings and disappearances.

Wolfinger said the FBI lab in Quantico, Va., is beginning to provide new leads through its analysis of evidence found at the crime scene, but there is no suspect yet in the deaths or in the disappearance of the children.

The FBI (search) on Monday offered a $100,000 reward for information about the children in addition to a local reward of about $7,500. At least 20 FBI employees are working on the case and the agency has sent profilers to look for clues.

Investigators have contacted everyone who attended a barbecue at the home on May 15, the last time the victims and missing children were seen alive, Wolfinger said. He would not say whether any or all of those who were present had been cleared of the crimes.