Osborn has spent nearly five years collecting evidence, including police reports, 911 call transcripts, autopsy results and crime scene photos.
She studied hundreds of other suicides, looking for patterns. One common theme she found was the presence of drugs and alcohol, but her daughter's autopsy showed that Morris' alcohol level was below the legal limit and there no drugs were in her system.
Osborn also studied her daughter's autopsy photos, looking for clues.
"Sheena and I, we wore the same mascara," Osborn said. "I knew that ... if you cry with this mascara on, that mascara just clumps up, your eyelashes are all clumped up and ... hers were perfect."
Experts say one would expect to see tears in a suicide of this kind.
Lee Williams, a veteran crime reporter who has covered this case extensively, said he also saw something that made it impossible to believe Morris killed herself.
"There's a photo of Sheena in the shower," Williams told "20/20." "Her feet are caked with sand and debris, yet there's no debris on the white floor, on the shower or on the white floor of the bathroom immediately outside the shower."
"Either Sheena was carried in there, post mortem and hung, or she somehow levitated into that room," Williams said.
Osborn was eventually able to have three independent forensic experts examine all the evidence and all three came to the same conclusion: Morris' death was not a suicide. To them, that hotel room appeared to be a staged crime scene. Armed with three affidavits from those experts, Osborn met with the medical examiner, who then reclassified Morris' manner of death as "undetermined pending further investigation."
Last October, the Florida Department of Law Enforcement decided that the case needed to be re-opened.
A Fiance With Nothing to Hide
Almost five years after the death of his fiance, Genoese said he was a victim too.
"I'm being victimized because I cared about someone," Genoese, who is now 49, told "20/20."
Genoese welcomed the new investigation, because he insisted he had nothing to hide.
"I have people that saw me that night," Genoese said. "What would be my motive?"
The image of his relationship with Morris, painted by her friends and family, Genoese said, is not a true one. In fact, Morris was often depressed around the time of her death, according to Genoese.
The reinvestigation into Morris' death is ongoing and a decision on whether to uphold the Bradenton Beach Police Department's original suicide ruling or classify the death a homicide and bring charges against a suspect is expected soon.
Osborn believes the question is already settled.
"When there's a trial and the jury finds the suspect guilty," Osborn said, "that chapter will be over."