BLOOMINGTON, Ind. — The mother of a missing Indiana University student Lauren Spierer expressed disappointment Wednesday that only one of her daughter’s friends has shared information with police that might lead to her whereabouts.

“I am extremely disappointed” Charlene Spierer said while encouraging others to come forward with any information at that may help police.

“No clue is too small,” Charlene Spierer said, her voice breaking up as she held back the tears while reading out the post office box address she and her husband opened for anonymous tips.

Police assured the public that their efforts to find the 20-year-old continue. “I know that our meetings have become less frequent and we have what seems to be less to talk about, this investigation is very much ongoing,” Bloomington Police captain Joe Qualters said, adding that police meet every day to work together and compile and exchange information.

“We have interviewed everyone on the secondary tier,” Qualters said, explaining Spierer’s most immediate friends and possible witnesses were interviewed first, and now all the individuals whose names had come out of the first set of interviews has also been questioned.

Police have reviewed 300 hours of video, including the images of the 20-year old just hours before she vanished, and still have more to analyze.

Robert Spierer, the missing fashion student’s father, echoed the police captain’s request for volunteers to participate in the search.

“Every day we could use a little bit of help,” Spierer said, thanking the volunteers who had already spent time looking, including those with horses. A significant amount of land still needs to be covered, he said, asking landowners to be patient with searchers on their property.

The blonde student who weighs less than 100 pounds was last seen on June 3 after returning from a night out with friends in Bloomington, Ind. An extensive investigation and many large-scale searches have so far failed to turn up any significant leads.