VANDALIA — Mary Lauterbach was planning to visit North Carolina before Christmas because her daughter Maria was eight months pregnant and could not travel.

Mary Lauterbach had "a very normal conversation" with the 20-year-old Marine when they discussed the visit in a phone call on Dec. 14. Lauterbach is a lance corporal stationed at Camp Lejeune.

That evening, a man whom Maria Lauterbach rented a room from off the base, called the Lauterbachs to "indicate he thought she had gone someplace," said Lauterbach, assistant director of donor relations at the University of Dayton.

"We thought that was very strange so we started trying to call her and her cell phone was turned off," she said.

Authorities found Lauterbach's cell phone Dec. 20 near the main gate at Camp Lejeune. Her car was found at a bus station in Jacksonville, about six miles from the base.

The family has been in daily contact with authorities in North Carolina.

"It's a mystery to them, too," she said. "She just dropped off the map."

Maria Lauterbach is the niece of Steve Lauterbach, who was among 52 Americans taken hostage in Iran in 1979.

Onslow County Sheriff Ed Brown said Wednesday investigators have searched her home and car, but are still left with "unanswered questions."

"I don't like the gut feelings I got with the information thus far," he said. "I hope I'm wrong, but we're going to work either way to find out where this young lady is."

Brown said Mary Lauterbach told investigators her daughter was due to testify about an incident she witnessed at the base, but had no further information. Mary Lauterbach also said someone vandalized her daughter's car after the incident.

Lauterbach has been a personnel clerk assigned to the 2nd Marine Logistics Group, II Marine Expeditionary Force since Nov. 23, 2006.

Base public affairs said the command is cooperating with the sheriff's department investigation.

The statement also said: "This case involves a member of our Marine Corps family and we continue to be hopeful for her safe return and our thoughts and prayers are with her family and friends during this time of concern."

Mary Lauterbach and her brother planned to travel to North Carolina on Dec. 21, but investigators "asked us to stay put because they really thought maybe she was frustrated and she would be coming back to town."

Even so, they traveled there last weekend.

"Since we went down there, it's been a lot more active," she said.