$1M Reward In Natalee Case

(CBS)  Natalee Holloway's mother, Beth Holloway Twitty, clinging to hope of seeing her daughter again, alive, says the reward in the case has been upped once more: "We're going to be able to now raise the reward for the safe return of Natalee from $200,000 to $1 million."

The Alabama teenager disappeared six weeks ago in Aruba.

And, reports CBS News correspondent Trish Regan, Beth Holloway Twitty is vowing to stay on the island until she learns what happened to her daughter.

"We're just so hoping that any information that someone has, (that) they would just feel comfortable to please come forward," she says.

Aruban authorities have now handed over to the FBI transcripts of interviews with everyone questioned in the case, including 17-year-old Joran van der Sloot, who's still being held in connection withy Holloway's disappearance.

The FBI is also analyzing a hair sample from a piece of duct tape found along the shore.

In addition, there are also reports of at least one witness who saw a car with three people inside on the night Holloway disappeared.

A private, volunteer search team from Texas is heading back to the island,

armed with additional equipment

to try to find some trace of Holloway.

"We actually roll it over the ground and it actually measures the density of the ground, so if there's an area that's been dug up or an area that a body has been buried in, it will actually show a hollow spot where a body is," explains Tim Miller of EquuSearch.

This is still far from a "cold case," Regan points out. The reward money keeps going up, and new pieces of the puzzle are slowly emerging. But there have also been plenty of false leads, in a mystery that is proving difficult to solve.