CHARLOTTESVILLE, Va. —Noting their heart-wrenching wait for answers, the parents of a missing University of Virginia student appealed Saturday for whoever is responsible for her disappearance three weeks ago to help them find their daughter.

Sue and John Graham, whose 18-year-old daughter, Hannah, disappeared on Sept. 13, issued a written and videotaped statement describing the case as a nightmare and noting that despite thousands of tips from the public, the college sophomore has not been found.

“Somebody listening to me today either knows where Hannah is, or knows someone who has that information. We appeal to you to come forward and tell us where Hannah can be found,” Sue Graham said in the taped statement. “John has already said that this is every parent’s worst nightmare … Please, please, please help end this nightmare for all of us. Please help us to bring Hannah home.”

Both parents wore blue collared shirts, along with buttons bearing their daughter’s picture and orange ribbons. Sue Graham took deep breaths and read her statement with a shaky voice, fighting tears as her husband put his arm around her several times.

Jesse Leroy Matthew Jr., a former college football lineman and sometime cab driver, has been charged with “abduction with intent to defile” in the disappearance. Police say forensic evidence also connects the 32-year-old Charlottesville man to the 2009 slaying of Morgan Harrington, a 20-year-old Virginia Tech student.

The Grahams thanked the investigators as well as members of the public who have offered support.

A search team of about 110 people including law enforcement officers and trained volunteers was combing the fields and countryside around Charlottesville on Saturday. Searchers have been out every day since the student was reported missing Sept. 14.

Mark Eggeman, search and rescue coordinator for the Virginia Department of Emergency Management, said his team was focusing on 200 square miles surrounding downtown Charlottesville and had covered just under half of that ground. A law enforcement computer mapping specialist has been brought in to help the team piece together the areas it has covered into a master planning map.

“It’s a lot about just trying to connect dots,” he said.