Natalee's mother, Beth Holloway Twitty, has been working tirelessly since last May, trying to unravel the mystery of her daughter's disappearance.
"You know she was 18 years old. She was on her senior trip. They were in this establishment of legal age," she says. "I'm certain they were drinking. We never even tried to say that they weren't, you know. But I have to ask myself, you know, 'Should that cost her life?' No. It shouldn't."
Police interviews with hotel staff, local bartenders, and her friends reveal that Natalee had spent much of the day with a drink in her hand.
"Do you know if Natalee could handle her alcohol?" Roberts asked.
"Yes," said Cain. "She was never somebody to be out of control if she had been drinking at all."
"When you hear stories, like people started drinking in mid-afternoon and drank through the night. Does that sound accurate?" Roberts asked.
"Yes," Claire Fierman said.
Fierman and Cain agreed that the drinking was kind of excessive.
48 Hours has learned that the Aruban investigation turned up another disturbing detail.
Asked if he has been able to confirm whether Natalee purchased or consumed illegal narcotics during her stay in Aruba, Dompig says, "We have statements claiming that she, that she had drugs."
What kind of drugs?
"I cannot say," Dompig replied.
Dompig notes that police don't have any proof that Natalee used drugs but "that they saw her with drugs in her possession."
Had Natalee's friends heard stories of people taking drugs?
"No. The only thing I heard about drugs is there were like people at the hotel that weren't with us that would like offer stuff to people. I was never offered drugs and I never even saw 'em," said Fierman.
However, police do believe that Natalee's judgment was impaired that night. Her friends were surprised that she was last seen willingly getting into a car with three strangers, 17-year-old Joran van der Sloot, 21-year-old Deepak Kalpoe and his brother, 18-year-old Satish Kalpoe.
Fierman says it would have been out of character for Natalee to voluntarily get into a car with three boys. "It frustrates me so much because I feel as much as, like, we say that, no one believes us 'cause you hear all that stuff," she says. "But, from the bottom of my heart, that is extremely out of character and not something that Natalee Holloway would ever do."
Holloway's mother agrees. "No way would she have left her friends and placed herself knowingly what she was getting into. They just took her when she just … There's no way."
"Do you think she may have been vulnerable because she had been drinking too much?" Roberts asked.
"Very much so," Cain replied.
Since Natalee disappeared almost 10 months ago, her mother has used any opportunity to keep the story alive to pressure the government of Aruba to solve this case.
"There are just no words to explain the frustration level that we have had to experience in dealing with officials from the island of Aruba," she says.
Last fall, Twitty called for a boycott of Aruba. The island's tourism industry has suffered: Travel bookings are off more than 4 percent from a year ago.
Does she still support a boycott of Aruba?
"The only leverage that we have in getting any traction in the investigation is when they feel the effects of a boycott," says Twitty.
According to Deputy Chief Dompig, the boycott is not the only thing that has cost Aruba dearly. He says authorities have about $3 million, on this investigation. "Which is about 40 percent of our operational budget," he explains.
As far as Beth Twitty is concerned, there has always been a simple solution to solving this case: Just ask the people last seen with Natalee — Joran van der Sloot and Satish and Deepak Kalpoe.
"If they had just gotten the suspects within the first 48 hours like they were supposed to have done, then they wouldn't have spent anything," she says.