Investigators trying to determine what happened to Natalee Holloway (search) focused their search efforts Wednesday on a pond near where the U.S. teen was last seen nearly two months ago.

Authorities used a large pump to drain the pond across from the Marriott Hotel (search) while investigators await the results of DNA analysis from labs in the Netherlands and the United States.

Authorities declined to discuss the exact purpose of draining the pond but confirmed it was part of the investigation into Holloway's disappearance on May 30 — the final night of a high school graduation trip to the Dutch Caribbean island. The job was expected to be finished later Wednesday.

Crews had hoped to finish late Wednesday but it was taking longer than expected to drain the pond. By early Thursday, authorities should have a clearer view of the bottom so they can pinpoint areas to search, said Gabriel Kelly (search), a spokesman for the fire department, which was coordinating the effort.

Holloway's stepfather, George Twitty, who was at a nearby hotel waiting for results of the search, said police asked the family not to watch as they worked behind a fence to clear the water.

"It's the first time the fire department, the police and other authorities have collaborated on such a huge search," the stepfather said Wednesday. "So they must know something. ... There's so much commotion, they must have a lead."

Holloway's mother, Beth Holloway Twitty, also said she was hopeful.

"I'm very encouraged about moving forward, and hopefully finding some answers that we've been waiting for, for a long time, and everyone has been," she said on ABC's "Good Morning America."

The activity came a day after Holloway's stepfather said two new witnesses had come forward with information about the night the 18-year-old from Mountain Brook, Ala., disappeared.

One witness told investigators that he saw Joran van der Sloot, the 17-year-old Dutch youth who has been detained as the main suspect, driving to a tennis club across the road from the Marriott around 2:30 a.m. the night Holloway disappeared, Twitty said.

The witness said van der Sloot tried to hide his face with his hands as he drove to the Racquet Club with two Surinamese brothers, Satish and Deepak Kalpoe, Twitty said. The Kalpoe brothers were detained as suspects and later released.

The stepfather said the account is significant because it places the three individuals near the hotel beach where van der Sloot says he left Holloway alone the last night she was seen in public.

"What's interesting is the time — 2:30 a.m. — when the three were supposedly on their way home," said Twitty, referring to their previous accounts to investigators.

The witness, a gardener whose name was not disclosed, gave his account to investigators Friday, Twitty said.

The Kalpoe brothers first told police that they and van der Sloot dropped Holloway at her hotel around 2 a.m. the morning of May 30. Later, they said they had lied to protect their friend and that they had dropped the Dutch youth and Holloway at a beach near the hotel.

A second new witness told a private investigator hired by Holloway's family that she saw van der Sloot and the Kalpoe brothers drive into the Racquet Club three times that same night. The woman, who lives nearby, has not yet spoken with investigators, he said.

Aruban authorities did not comment on the stepfather's statements.

An attorney for van der Sloot, Richie Kock, said authorities had not told him about the new witnesses. Lawyers for the Kalpoe brothers were not immediately available for comment.

Aruban authorities said this week that they have dispatched a prosecutor to consult with the FBI and brought in experts from the Netherlands as they investigate the disappearance.

Aruban investigators sent hair found attached to duct tape discovered along the shore of the island to the FBI crime lab in Quantico, Va., and to the Netherlands for DNA analysis.

The family on Monday increased the reward for information leading to the young woman's safe return to $1 million, from $200,000.

No one has been charged in the case, and van der Sloot is the only suspect still detained.

Holloway vanished after an evening of eating, drinking and dancing at a nightclub which she left with the three young men, hours before she was to catch a flight home at the end of a graduation trip with 124 classmates.