Investigators on Long Island are officially handling the death of fashion designer Martha Nolan-O'Slatarra as a homicide, multiple police sources have exclusively told Us Weekly. "It was a murder," stated one source emphatically. "As of right now, everyone's trying to build a case against [the suspect], but I couldn't say how close we are to an arrest." Nolan-O'Slatarra, 33, was found lifeless on August 5 on a boat that had been docked at a yacht club in Montauk. East Hampton Town Police were called to the Montauk Yacht Club on a report of an unconscious person, but by the time they arrived, Nolan-O'Slatarra had been dead for hours. Passersby tried reviving Nolan-O'Slatarra, who was a popular bikini and clothing designer in the Hamptons. Investigators did speak to people who said they had heard screaming coming from the yacht club's dock on the same day she was discovered dead. At this point, an official cause of death remains pending for the Irish native, but some of the marks on Nolan-O'Slatarra's body led medical examiners to conclude she had been a recent victim of violence. Nolan-O'Slatarra was the founder of the East x East clothing brand. She also launched the Brand Growth Consultants company, according to her Instagram bio. Martha Nolan-O'Slatarra's Family Searching for 'Details' After Her Death East x East was founded as a "sustainable resort wear brand" and "on the belief that fashion should not come at the expense of our planet," according to the brand's website. The clothing company sells a combination of accessories, clothing and swimwear for both men and women. Nolan-O'Slatarra was living in Montauk with her long-term boyfriend, who sources said has been ruled out as a suspect in her murder. According to her LinkedIn page, Nolan-O'Slatarra studied at University College Dublin and graduated with a bachelor's degree in business administration and management and a master's degree in digital marketing. After a few years working in Ireland, Nolan-O'Slatarra had relocated to New York City in 2015 when she was 26. Sources said there were only trace amounts of cocaine found in Nolan-O'Slatarra's system. The New York Post reported Nolan-O'Slatarra had arranged to meet with investor and boat owner Christopher Durnan, 60, to discuss a possible business deal shortly before her death. Nolan-O'Slatarra wanted to meet with Durnan about a possible investment East x East. However, a family source claimed to the Daily Mail that the insurance bigwig was keen on turning the evening into a "romantic interlude." The source added: "He was the one driving the boat as to when and where they were meeting." Durnan's lawyer, Robert Holdman, told New York magazine back in November that the pair's meeting was only about business, though he claimed the two had also "actually dated." Holdman then reversed course on that label when asked for more information by New York magazine, claiming Durnan told him that he loved Nolan-O'Slatarra as a friend and that he wasn't involved in a "hard relationship" with her. Durnan also allegedly claimed to Holdman that he and Nolan-O'Slatarra were sitting on the boat when she suddenly went limp and that he unsuccessfully attempted to revive her by performing CPR.