( CNN ) -- The family of a woman whose naked and bound body was found hanging in a Southern California mansion two years ago has filed a federal lawsuit accusing three people of plotting her death . The San Diego County medical examiner ruled that Rebecca Zahau committed suicide , but a lawsuit filed Friday by her mother and sister contends she was the victim of a murder plot devised by her millionaire boyfriend 's brother , ex-wife and the ex-wife 's twin sister . Zahau 's boyfriend , Jonah Shacknai , owned the Coronado , California , vacation home where she was found dead on July 13 , 2011 . His 6-year-old son , Max , suffered a fall in the same home two days earlier and died in a hospital on July 16 , 2011 . The lawsuit filed by the dead woman 's mother , Pari Zahau , and sister , Mary Zahau-Loehner , does not detail the alleged plot , but it contends each defendant `` participated in some manner in the planning , implementation , execution and subsequent concealment of the scheme to murder Rebecca Zahau . '' The defendants named are Adam Shacknai of Memphis , Tennessee ; Dina Shacknai of Phoenix , Arizona ; and Nina Romano from Stockton , California . Dina Shacknai is the mother of Max , the boy who died from the fall . `` Defendants intentionally , willfully , wantonly and maliciously threatened to cause immediate physical harm to Rebecca by threatening to stalk , attack , choke , gag , bound , and hang her at the premises , '' the complaint said . Efforts by CNN to reach the defendants or their lawyers for comment were unsuccessful Sunday . After Zahau 's death was ruled a suicide and San Diego County officials refused to pursue criminal charges , Jonah Shacknai asked the California attorney general 's office to investigate his son 's fatal fall and his girlfriend 's hanging . He said he hoped a state inquiry would bring a `` dignified resolution for everyone who has been touched by the horrible events of this summer . '' The attorney general cited the `` state 's scarce resources '' in a letter declining to investigate , but Zahau 's family hired their own investigators to challenge the findings that she committed suicide . A renowned forensic pathologist hired by the family said four bruises found on the top of her head indicate trauma not readily explained by the hanging . He said in September 2011 that it was just one of several reasons he would n't have ruled the death a suicide . Authorities first went to the home , in the San Diego suburb of Coronado , on July 11 after getting a call from Zahau 's 13-year-old sister reporting that Max had fallen down the stairs and was not breathing , Coronado police Cmdr . Mike Lawton said . Zahau , her sister and the boy were the only ones in the residence at the time of the incident . Police arrived within two minutes , followed a minute later by firefighters who , after finding the boy unconscious on the floor , `` began lifesaving measures immediately , '' Lawton said . But despite extensive medical treatment , Max Shacknai died five days later . The medical examiner ruled the boy 's death an accident . On July 13 , authorities got another 911 call from the home . This time , it was Adam Shacknai , Jonah Shacknai 's brother , reporting that he found Zahau hanging , San Diego County Sheriff Bill Gore said . Adam Shacknai , who was staying in a guest house that morning , told investigators that he climbed onto a table and cut the body loose before investigators arrived , authorities said . Gore said investigators were comfortable with the brother 's account . Jonah Shacknai , a lawyer and the founder and CEO of Medicis Pharmaceutical Corp. , was at a children 's hospital or a Ronald McDonald House from the time when investigators believe the suicide happened to the time Zahau 's body was reported , San Diego sheriff 's Lt. Larry Nesbit said . The autopsy concluded that Zahau was `` alive when she went over the ( second-floor ) balcony '' with a T-shirt wrapped around her neck , the medical examiner said . There was no evidence of a struggle or a sexual assault , or that she was rendered unconscious or incapacitated , adding that `` her feet were dirty , consistent with standing on the dirty balcony , '' he said . Though investigators do n't know the order of events , they believe she removed her clothing , painted a message , cut a rope into sections , secured the long portion to a bed , bound her feet , placed the rope and the shirt around her neck , fashioned wrist bindings , secured her hands in the binding behind her back , moved to the balcony , leaned over the rail and fell , San Diego County sheriff 's Sgt . Dave Nemeth said . Nemeth said one person told investigators that in January , Zahau had `` lost weight , seemed stressed , was not sleeping well and was not exercising , which was abnormal for her . '' Other interviewees indicated that `` Rebecca was distraught over Max 's injury , '' Nemeth said . But Zahau family attorney Anne Bremner had previously said that one of Zahau 's sisters , who talked to her the night before her death , said Zahau `` was completely fine '' and did n't feel guilty about Max Shacknai 's fall . `` My sister never had a psychiatric problem , never ( had ) been on psychiatric medication and never had attempted suicide , let alone ever talked about harming herself , '' Mary Zahau said in an interview weeks after her sister 's death .
The San Diego County medical examiner ruled Rebecca Zahau 's death a suicide . Rebecca 's family did a private investigation after officials would n't press criminal charges . Lawsuit accuses boyfriend 's brother , ex - husband and ex - wife 's twin of plotting her death . Zahau died two days after her boyfriend 's brother suffered a fatal stroke in the same home .