Investigators said Monday they will conduct DNA tests on blond hair attached to duct tape that was found along Aruba's coast to see if it came from Natalee Holloway (search) in a possible break to the six-week-old mystery.

A park ranger found the duct tape while collecting trash Sunday on rocks at Boca Tortuga (search), an inlet near a series of caves on Aruba's northeast coast, said National Park Ranger Service spokeswoman Dilma Arends.

Boca Tortuga is on the opposite side of Aruba from where the 18-year-old was last seen in public, and her father expressed little hope that the find would yield an important clue.

"We've had a lot of information that turned out false," David Holloway (search) said as he prepared to leave Aruba and return home to Meridian, Miss.

The ranger who made the find, Mario Rasmijn, said there were several strands, each about 12 inches long, and that some were light blond and others were dark.

The hair will be sent to the Netherlands for DNA analysis, said police spokesman Edwin Comemencia. Aruba, a Dutch protectorate, doesn't have a lab to conduct the genetic testing.

A separate test will be conducted by the FBI at its lab in Quantico, Va., said FBI spokeswoman Judy Orihuela in Miami.

It was unknown when the results would be disclosed.

Searches by Dutch marines, Aruban police, and some 2,000 volunteers have found no trace of Holloway, of Mountain Brook, Ala., who was last seen in public in the early hours of May 30, at the end of a high school graduation trip to the Caribbean island.

A volunteer group from Dickinson, Texas, that had searched for three weeks left the island Sunday.

A 17-year-old Dutch resident of Aruba, Joran van der Sloot, has been detained in connection with Holloway's disappearance, but no charges have been filed.

David Holloway said he tried to visit van der Sloot in jail Saturday because "I wanted Joran to meet with me and tell me face to face what happened."

Authorities did not allow the meeting and Holloway ran into the detained youth's father, a judge in training on the island, outside the jail.

Holloway said he gave the elder van der Sloot, Paul, three books to pass along to his son -- the Bible and two Christian inspirational works. It was not immediately known if Joran received the material.

Paul van der Sloot was detained on June 23 for allegedly aiding his son, but released four days later by a judge who ruled there was not enough evidence to hold him.

Outside the jail, the two men exchanged a few words. "I said I was a forgiving person," and the Dutch father's eyes filled with tears, Holloway said.

"He said he understands my situation, that he's a father, too, and that he'll do anything for his son," Holloway said.

Authorities can hold van der Sloot until Sept. 4, when he must be charged or released. Six other men detained at various times during the investigation have been released.

Also over the weekend, the missing teen's family posted a new reward of $175,000 for her safe return in addition to the $50,000 already offered for a tip to her whereabouts.