Robert Adams arrested over disappearance of nurse Mary Wallace Pauline Biddle holds up a picture of her friend Mary Louise Wallace in 2010. A man has been arrested in connection with one of Sydney's greatest missing person cases, the disappearance and suspected murder of a woman on the city's north shore nearly 30 years ago. Mary Louise Wallace, who worked as a nurse at Hunters Hill Private Hospital, disappeared on a night out with friends at a bar in Crows Nest on September 24, 1983. Police said the popular 33-year-old, from Drummoyne, had been befriended at the Alpine Inn wine bar by Robert Adams, who offered her a lift home. Mary Louise Wallace was 33 when she disappeared in 1983. She was never seen again, and her body has never been found. Early on Friday, detectives from the Homicide Squad's Unsolved Homicide Team arrested Mr Adams, now aged 62, in Gladesville. He was taken to Parramatta police station, where detectives say they expect to charge him with the murder of Ms Wallace. The arrest is the culmination of more than 30 years of investigations, including the force's biggest homicide investigation, coronial inquests, re-investigations, excavations and hundreds of interviews. Last year, Ms Wallace's sister, Anne Fraser, pleaded for information about her sister's disappearance as police announced a $100,000 reward for information. At the time, Ms Fraser said the fact that no one had ever been charged over the disappearance of her sister had haunted her. "I think that's why I'm so emotional," she said. Because we have never known. If even 20 years ago it had been cleared up, it would be different. I wouldn't be here, a quivering mess, because there is resolution and then you grieve ... and it makes it much easier. Ms Wallace's parents both died without knowing what happened to their daughter. In the 1980s, police received an anonymous letter claiming that Ms Wallace's body was buried under a rock in the Lane Cove National Park. Yet two operations in the national park, including extensive geo-radar testing and excavation in 2010, found nothing. Police will provide more information about Friday's arrest at 10am.