BLOOMINGTON, Ind. (CBSNewYork/AP) — The investigation into the disappearance of an Indiana college student more than two weeks ago yielded no visible results Monday as police confirmed that a truck seen in the area near the time of the coed’s disappearance was not connected to the case.

Bloomington police Capt. Joe Qualters said Monday that investigators received more than 500 tips after releasing images from security cameras last week showing a white truck passing through the downtown area in which Lauren Spierer was last seen early June 3 after a night of partying with friends.

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Qualters said the tips, including photos of the truck, helped police identify the business it belonged to. He said investigators interviewed the business owner and combed the vehicle but found no evidence it was tied to the disappearance of the 20-year-old sophomore from Westchester County.

WCBS 880’s Catherine Cioffi reports: Search Continues For Lauren Spierer

“That vehicle has been eliminated from consideration,” he said.

The news came a day after investigators searched an area south of Martinsville following a tip of a suspicious odor in the area. Qualters said investigators found a mound of earth that appeared to be fresh and measured about 4 feet by 2 feet but no evidence it was linked to the Spierer investigation.

“They found absolutely nothing,” Qualters said.

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He said the mound was believed to be tied to recent utility work.

Still, police and Spierer’s parents remained resolute about continuing the efforts. Nearly 300 people turned out over the weekend to help with searches despite inclement weather, Qualters noted.

“We are very encouraged by the interest as well as the commitment by a lot of people who realize how important this is to us,” Qualters said. “The only frustration is that we are not able to provide an answer at this point. … We will not be satisfied until we are in a position to find out what happened to Lauren.”

Spierer’s mother, Charlene, issued a personal plea to anyone with knowledge of what happened to her daughter.

“We all come to a crossroads in our lives. You have a choice of which road you want to take. We all have that defining moment that defines who we are,” she said.

“I am begging and pleading with you to take the high road, to be the person who defines yourself as the person who helped us.”

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(Copyright 2011 by The Associated Press. All Rights Reserved.)