The sister of one of the missing women linked to accused murderer Robert Durst has begged the multi-millionaire to come clean to help end nearly 18 years of agony for her family. Speaking exclusively to Daily Mail Online, yoga teacher Allison Modafferi urged Durst to be honest with police if he knows anything about what happened to her sister, honors student Kristen Modafferi. 'If he — or anyone — knows anything, please come forward so we can have some answers,' pleaded Allison, who is expecting a daughter in June. 'It's been nearly 18 years so as a family we would welcome anything that could put our minds at rest,' she added. SCROLL DOWN FOR VIDEO . Without a trace: Yoga teacher Allison Modafferi (left) urges Robert Durst to be honest with police if he knows anything about what happened to her sister, honors student Kristen (right) Family affair: From left, mom Debbie, Kristen, sisters Lauren, Meghan (in front) and Alliston and dad Bob at a family wedding in early 1997. Before they retired Bob was an engineer and Debbie an elementary school teacher, have both now retired . Durst, who is worth an estimated $100 million, was arrested in New Orleans last weekend. Police believe he was preparing to flee the country as he was found in a hotel room with a latex mask, false ID, a loaded Smith & Wesson .38 caliber revolver with one spent shell casing and $42,000 in cash. The family of Kristen (right) want him to help end their agony . 'We hope that one of these days we will get some answers as to what happened to Kristen.' Kristen disappeared from San Francisco in 1997. Oakland Police now say there is no hard evidence to suggest that Durst was involved, even though he was living in the city at the time. But In a statement, issued through family friend Joan Scanlon-Petruski, parents Bob and Debbie Modafferi pointed out that the FBI, which had investigated Durst before, could come up with new evidence now.Cops in the northern California town of Eureka are probing whether he could have been involved in the disappearance of another teen, 16-year-old Karen Mitchell who vanished just five months after Kristen. Durst, 71, was sensationally acquitted of the 2001 murder of neighbor Morris Black and has long been suspected of killing his first wife, Kathie, and then murdering long-time friend Susan Berman because she knew too much. He was shockingly caught on tape saying 'I killed them all,' at the end of the HBO documentary The Jinx: The Life and Deaths of Robert Durst. Durst, who is worth an estimated $100 million, was arrested in New Orleans last weekend, shortly before the finale of the series aired. Police believe he was preparing to flee the country as he was found in a hotel room with a latex mask, false ID, a loaded Smith & Wesson .38 caliber revolver with one spent shell casing and $42,000 in cash. A small amount of marijuana was also discovered. He is now on suicide watch as he awaits trial in Louisiana on gun and drug possession charges and extradition to California to face a murder trial in the Berman case. Home sweet home: Last December the family sold the five-bedroom, four-bath family home in an upscale development south of Charlotte where Kristen and her three sisters had grown up . Summer in the city: Kristen during her freshman year at North Carolina State University. She moved to San Francisco on her 18th birthday, June 1, 1997. She planned to spend the summer in the City by the Bay before returning to her sophomore year at North Carolina State University where she was studying design . But as new interest has been aroused in Durst, he finds himself linked to cases in at least four states, including the disappearances of Modafferi and Mitchell. Kristen Modafferi moved to San Francisco on her 18th birthday, June 1, 1997. She planned to spend the summer in the City by the Bay before returning to her sophomore year at North Carolina State University where she was studying design. The previous year she was one of the inaugural recipients on the now-highly regarded Park Scholarships which put a premium on travel and service. Within days she started work at Spinelli's coffee shop in the Crocker Galleria in San Francisco's financial district to help pay for a photography course she was due to start at UC Berkeley the day after she vanished. On the day of her disappearance she asked a co-worker for directions to Baker Beach. After she went missing police dogs tracked her scent to the water's edge at nearby Land's End Beach. The last sighting of Kristen was walking through the upscale mall with a blonde woman, who has never been identified. Speculation has risen in recent days that it was in fact Durst, a noted cross-dresser. 'That blonde woman has never come forward and no-one has ever found her,' said Allison Modafferi. Scholar: Kristen at her high school graduation. She was one of the inaugural recipients on the now-highly regarded Park Scholarships which put a premium on travel and service. This is not the first time that Durst has been linked to Modafferi or to Mitchell, who was 16 when she was last seen in Eureka, California, five months after Kristen's disappearance. Durst owned a house in San Francisco at the time Kristen vanished and he was known to be living in Trinidad, California, some 25 miles north of Eureka when Karen went missing after getting into a car. A police sketch of a man driving that car bears an uncanny likeness to the troubled New York property heir. Author Matt Birkbeck first connected Durst to the two missing teens in the 2003 paperback edition of his book A Deadly Secret: The Strange Disappearance of Kathie Durst. The FBI checked Durst out at the time but could not prove that he was connected to either woman. Allison Modafferi is also skeptical even now that Durst, who was found not guilty of the 2001 murder of Black, his neighbor in Galveston, Texas, despite admitting that he chopped his body up and threw it in the sea, will be charged in connection with her sister's disappearance. 'There is just not a lot of evidence,' she told Daily Mail Online. 'The FBI looked at him a few years ago and came up with nothing. 'We have had so many leads over the years that have led nowhere.' The family has never given up hope that Kristen, who would now be 35, is still alive, despite the fact there has been no trace of her for nearly half of her life. They dismiss the possibility that she might have staged her own disappearance. 'We were a very close family — we still are a very close family,' said Allison. 'And there are no signs that she wanted to disappear. She hadn't packed her bags or withdrawn money or anything like that.' But still the family clings to the hope that she is still alive. In obituaries placed in the Charlotte Observer after the deaths of her grandfather Tony Modafferi in 2002 and his widow Lillian in 2006, the family wrote that they left 'four granddaughters, Allison, Kristen, Lauren and Meghan.' Joan Scanlon-Petruski of The Kristen Foundation, a non-profit set up to help find missing adults, told Daily Mail Online that the family is hoping that the Durst link may finally bring some closure to their 18-year ordeal . 'Of course we live with that hope,' said Allison, 38. 'But it has been a very long time.' And as for the chance that she has been held captive for a dozen and a half years, she added: 'There is a part of each of us that hopes for something like that, but it is hard to imagine what the past 18 years would have been like for her if that were the case.' Kristen's parents, Bob, an engineer and Debbie, an elementary school teacher, have both now retired. Last December they finally sold the five-bedroom, four-bath home in an upscale development south of Charlotte, that Kristen and her three sisters had grown up in, and moved to Florida. In a statement, issued through family friend Joan Scanlon-Petruski, Bob and Debbie Modafferi pointed out that the FBI had investigated Durst before. 'It is possible though that the ongoing interrogation of Durst by law enforcement that's taking place right now could uncover new information that could be of value and lead to the truth about what happened to Kristen,' they added. Scanlon-Petruski, who runs The Kristen Foundation, a non-profit set up to help find missing adults, told Daily Mail Online that the family is just hoping that the Durst link may finally bring some closure to their 18-year ordeal. 'Robert Durst is crazy and he has shown he is not willing to admit anything,' she said. 'I certainly want it to be him,' Scanlon-Petruski added. 'Then we would be able to find out at least something, but we have been disappointed so many times in the past.' But police in Oakland, California say there is nothing new to link Durst to Modafferi. 'The Oakland Police Department conducted an investigation with the assistance of the Federal Bureau of Investigation regarding the 1997 disappearance of Kristen Modafferi. The investigation was open and active for several years. At this time we do not have any evidence that indicates Robert Durst was involved in her disappearance.' The department said in a statement.
Kristen Modafferi, 18, from Charlotte, North Carolina, disappeared in San Francisco without a trace in 1997 . Her sister Allison urges Robert Durst to be honest with police if he knows anything about what happened . The last sighting of Kristen was walking through the upscale mall with a blonde 'woman'
Speculation has risen in recent days that it was Durst, a known cross-dresser . Oakland Police have ruled out a link but the FBI has investigated the connection between Durst and Kristen's disappearance . Parents Bob and Debbie Modafferi believe 'the ongoing interrogation of Durst...could uncover new information'