(CNN) — The parents of missing University of Virginia student Hannah Graham issued a new appeal for the whereabouts of their daughter on Saturday, saying despite an arrest in the case, thousands of tips and hours of searches, someone must have critical information yet to be revealed.
“Somebody listening to me today either knows where Hannah is, or knows someone who has that information,” the mother, Sue Graham, says in a video released by the city of Charlottesville, home to the university. “We appeal to you to come forward and tell us where Hannah can be found.”
“Please, please, please help end this nightmare for all of us,” she continues. “Please help us to bring Hannah home.”
Hannah Graham, an 18-year-old in her second year at the university, was last seen September 13 in area of Charlottesville known as the Downtown Mall.
Thirteen days later, police in Texas arrested a suspect in the case, Jesse Matthew, 32. Matthew, who investigators say is the last person believed to be with Graham, was extradited to Virginia, where he was charged with abduction with intent to defile and is being held in jail.
Still, authorities say they don’t know where Graham is. They are offering a $100,000 reward leading to her safe return. More than 3,000 tips about her possible whereabouts have come in, police spokesman Carter Johnson said.
In the video released Saturday, Sue Graham, standing with her husband, John, thanks everyone who has participated in the search, contributed money to the reward fund, and given tips to police.
But with her their daughter still missing, the Grahams said they felt compelled to plead with anyone who might be hiding information.
“John has already said that this is every parent’s worst nightmare. That is true, but it is also a nightmare for our son, James, for Hannah’s grandparents and other members of our family, as well as for all of Hannah’s many friends here in Charlottesville and beyond,” Sue Graham said.
As part of the search effort, police asked owners of large parcels of property in surrounding counties to search their land and report back.
And searchers have used an aerial drone in the search — the first time, according to authorities, one has been used to look for a missing person in the state. The drone, with a high-quality camera, has been used to help searchers check vast tracts of land in the area.
‘Link’ between Graham case, death of another woman
Earlier this week, law enforcement sources told CNN that DNA links Matthew to the 2009 death of a different woman in Virginia, Morgan Harrington. Virginia State Police have said only that there is a “new forensic link” between Harrington’s case and Graham’s.
Harrington, a 20-year-old student at Virginia Tech in Blacksburg, went missing after attending a Metallica concert in Charlottesville in October 2009. She was last seen hitchhiking along U.S. 29 outside of Charlottesville, and her remains were found on a farm months later.
No arrests have been made in Harrington’s case, and the cause of her death still is under investigation.
CNN’s Athena Jones, Mike Ahlers and Ed Payne contributed to this report.