SAN DIEGO -- Nearly two weeks after 7-year-old Danielle van Dam disappeared, police again searched the home for five hours of a neighbor they have called a potential suspect in the case, 10News reported.

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Arriving in the Sabre Springs neighborhood about 6 p.m., officials -- including a high-ranking homicide lieutenant -- refused to say why they again were going through neighbor David A. Westerfield's house.

"The nature of the search warrant and what they are looking for will not be discussed," San Diego Police Department information officer Dave Cohen said.

Twice before, detectives took service dogs through the 50-year-old engineer's house two doors down from the van Dams' residence.

During the initial searches, officers carted off boxes and bags full of household items. In addition, police impounded Westerfield's sport utility vehicle and the motor home he'd taken to the arid region near Arizona the weekend of Danielle's disappearance.

A DNA sample submitted by Westerfield has been forwarded to an FBI crime lab in Washington, D.C., according to 10News.

Still, authorities have referred to the neighbor only as a "potential suspect" and have not taken him into custody.

Parents Plea For Help Finding Danielle

Brenda van Dam held a new photograph of Danielle, as she and her husband, Damon, spoke to reporters Thursday gathered outside their home.

Video

Watch Thursday's Press Conference With van Dams

Brenda van Dam said that she remains hopeful that her daughter, who is presumed by police to have been abducted, "is still alive and that she is coming home."

This week police began acknowledging that the odds of finding Danielle alive are waning.

"We are not real hopeful on her condition," said San Diego police Lt. Jim Duncan.

Damon van Dam expressed his gratitude to the hundreds of volunteers who have participated in the search -- both in San Diego and the Imperial County desert region.

He also announced that the headquarters of the volunteer effort to find Danielle would move to the Re-max Building at the corner of Poway and Pomerado roads on Monday.

In response to a query about how Danielle's two brothers were holding up, Brenda van Dam said: "They're hanging in there, they're afraid to be alone, they're still sleeping with us and we're going to seek counseling next week for them."

The activist father of kidnapping and murder victim Polly Klaas joined the van Dams at Thursday's briefing (pictured, above, right).

Marc Klaas -- who created the Polly Klaas Foundation, a missing-child advocacy and crime-prevention agency, following his 12-year-old daughter's 1993 abduction -- asked the community to respond to Danielle's plight as they would if their own child was missing.

"If somebody can come into a home and take a little child out of her bedroom it can happen to anybody," Klaas said. "Every child is vulnerable."