NEW YORK ( CNN ) -- Authorities in Aruba say they 're looking into new evidence that could lead to an arrest 3½ years after Alabama teenager Natalee Holloway disappeared on a senior class trip to the island . Alabama teenager Natalee Holloway disappeared while on vacation in Aruba with classmates in 2005 . Aruban police are investigating two new tips they hope will provide the corroborating evidence they need to make an arrest , lead prosecutor Hans Mos told CNN . He would not discuss details but said police again consider Dutch student Joran van der Sloot to be the prime suspect in Holloway 's disappearance . A new witness has emerged , authorities say , who can place van der Sloot and his father , Paulus van der Sloot , near a pond on the island at 4 a.m. on the day Holloway vanished . The witness told authorities he saw a young man , wet from the chest down and wearing only one shoe , running along a road from the pond to a fast-food restaurant . The witness said he saw the young man and an older man driving slowly down the road in a red Jeep about 10 minutes later . The pond was not among those searched in the early stages of the investigation , Mos said . A second witness , a former girlfriend of Joran van der Sloot , also told police he made suspicious-sounding comments while they were on the beach . The witness , publicly known only as Celes , told police van der Sloot said : `` Who knows ? You may now be on the beach with someone who is able to get rid of a corpse . '' Watch the latest developments in the case » . In addition , Mos said , two other witnesses have come forward . He declined to discuss those witnesses , other than to say he is hopeful the case can be solved . `` We are hoping to make a decision by the end of this year or early next year as to whether we will re-arrest [ the younger ] van der Sloot or not , '' Mos told CNN . Also key to the investigation , Mos added , is a Dutch journalist Peter De Vries ' videotaped interview with van der Sloot . In the interview , van der Sloot acknowledges a friend helped him get rid of her body . Read how van der Sloot `` lost no sleep '' over Holloway . Mos said he is confident that the tape , which he characterizes as a confession , is admissible in court . With the new tips and new witnesses whose testimony impeaches earlier statements by van der Sloot and his father , Mos said he might have enough evidence to solve the mystery of what happened to Holloway . The elder van der Sloot has told police he was at home , asleep in bed until 7 a.m. on the night in question . And , Joran van der Sloot has never been able to explain what happened to his tennis shoes , Mos said . Holloway 's father , Dave , said the new developments caught him by surprise . `` Well , I really hope it 's true , because they even have Joran on tape confessing , and I do n't know what could be better than that , '' he said . Van der Sloot 's family and attorney did not return phone calls . Natalee Holloway , 19 , a senior at Mountain Brook High School in suburban Birmingham , Alabama , was a vibrant member of the school band 's dance team , `` The Dorians , '' which is similar to the `` Rockettes . '' She was a straight-A student who planned to study pre-medicine at the University of Alabama . She vanished in May 2005 while on her senior class trip to the island . She was last seen at the popular night club Carlos ' n Charlie 's early on the morning her class was due to fly home . Her disappearance became the subject of a high-profile search and a massive media frenzy . Holloway family members and friends organized volunteer search efforts in Aruba that went on for months . Early missteps cost investigators valuable time and evidence . Police at first mistakenly arrested two men who had nothing to do with Holloway 's disappearance . And , investigators initially ignored information from witnesses pointing to the three young men last seen with Holloway that night . When Joran van der Sloot and brothers Deepak and Satish Kalpoe were arrested , they told conflicting stories . By that time , verifiable facts were hard to come by . Van der Sloot is a member of a prominent Dutch family in Aruba . At the time of Holloway 's disappearance , his father was a judge in training . Joran van der Sloot and the brothers Kalpoe were arrested and let go twice in connection with Holloway 's disappearance . While they were in jail , police and prosecutors sought corroborating evidence to piece together a motive and theory . They were not successful . Late last year , authorities closed the case without bringing any charges . `` We simply did not yet have the corroborating evidence to take this to trial and win a conviction , '' prosecutor Mos told CNN . `` If we had a body even to determine cause of death , then we could piece some thing together . '' In February , the videotape of van der Sloot 's taped admission surfaced on Dutch television . De Vries , a famed Dutch journalist , set up a hidden camera capturing van der Sloot talking about Holloway 's last moments and how her body was disposed of `` like an old rag . '' Since then , De Vries has set up another on-camera sting . It aired last week , showing van der Sloot meeting with undercover reporters who posed as Dutch sex industry bosses looking for Thai prostitutes to recruit to the Netherlands as sex slaves . In the tape , van der Sloot allegedly promises to supply Thai girls for prostitution in Holland and accepts 1,000 Euros as advance payment for his services . Apparently van der Sloot left the Netherlands late last year and has been living in Thailand for the last few months as a student . His whereabouts right now are unknown , but Aruban authorities are grateful for the tips that the Dutch documentaries have generated . They hope the tips will bring them closer to a resolution in the disappearance of Natalee Holloway .
Aruban prosecutor says new evidence has surfaced in Holloway case . Several new witnesses have come forward since televised interview . The U.S. State Department said it was aware of the report and is working with Aruba to "determine what additional information may be available" about Holloway's case. Have information ? Call Aruban prosecutor : 011-297-521-4100 .