SAN DIEGO -- The search for Danielle van Dam was aided Thursday by a group of Marines from Marine Corps Air Station Miramar, 10News reported.

MISSING Danielle van Dam 4 feet tall, 58 pounds Blue eyes, dirty blond hair Possibly wearing blue pajamas Watch Danielle Video Montage INFORMATION Danielle Recovery Center: (858) 485-4185 Tips: (619) 531-2000 Danielle Missing Flyer DISCUSSION Share your feelings, thoughts for van Dam family

More than 30 Marines looked for clues to the missing girl's disappearance in the brushy foothills off Highway 67 in the vicinity of Poway and Lakeside.

Organizers at the Poway-based Danielle Recovery Center are also planning a third weekend of searches in the desert, one in Borego Springs and one in Shelter Valley.

Meanwhile, a candlelight vigil in honor of the missing 7-year-old will take place at St. Timothy's Episcopal Church in Rancho Penasquitos at 7 p.m. Thursday night.

Friday evening, concerned citizens will join San Diego Police Department officials at a "town hall" meeting featuring a talk by Marc Klaas of Petaluma, whose own young daughter was abducted and murdered in 1993. That gathering will take place at Creekside Elementary, where Danielle attended second grade.

As they have regularly done over the last three weeks, Danielle's parents repeatedly met with the press in front of their upscale home this week, again urging the public to keep looking for the child.

Damon van Dam told reporters Wednesday that his family's ordeal "could happen to anyone."

"We were just like everyone else out there watching this now," he said. "We were the exact same people you are. ...This is an awful, awful thing, and just everyone else needs to know that this can happen to you."

"I think everyone takes it for granted, their security," added his wife, Brenda. "I mean, you're in your home, you're in a safe neighborhood -- you feel safe."

When the van Dams reported the girl missing the morning of Feb. 2, they told authorities that the last they had seen of her was when her father put her to bed about 10 the night before.

The parents are not suspects in the girl's disappearance, which is officially considered a case of abduction, authorities have said.

This week, SDPD crime lab workers returned to the van Dams' home to do some follow-up evidentiary work at the scene of her presumed kidnapping.

They removed closet doors from Danielle's upstairs room Wednesday "to continue processing (tasks) that we began several days ago," SDPD information officer Dave Cohen said.

"We will not discuss why those doors might be important to the case," he said.

Police have collected more than 100 pieces of what they call "potential evidence" from the family's Mountain Pass Road house, from neighbor David A. Westerfield's home two doors away and from two vehicles he owns.

Investigators have focused much of their efforts on Westerfield, who took a desert trip around the time Danielle disappeared.

Though the 50-year-old design engineer has come under close and near-constant law enforcement scrutiny, authorities have not taken him into custody and continue to refer to him only as a "potential suspect" in the case.

Investigators have searched his home and impounded his sport utility vehicle and motor home, and he has provided a DNA sample for analysis.

Police officials also disclosed this week that they are delving into previous area child-abduction cases to look for links to Danielle's disappearance.

In addition to looking through the sun-baked wastelands of neighboring Imperial County, teams of community volunteers have gone over considerable open territory in eastern San Diego-area communities in recent days.