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The 6-year-old son of a prominent pharmaceutical executive was likely assaulted and then sent plunging to his death over a balcony inside his father's San Diego mansion last year, according to a report by two medical experts.

The new report concludes that Max Shacknai, son of Medicis Pharmaceuticals chief Jonah Shacknai, was the victim of a homicide -- not an accident, as authorities had ruled in the July 2011 death inside Shacknai's historic San Diego Bay mansion.

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"It's shocking and horrifying for me," said the boy's mother, Dina Shacknai, who is calling on the Coronado Police Department to reopen their probe into his death. Shacknai hired Dr. Judy Melinek, a San Francisco-based forensic pathologist, and Dr. Robert Bove, an injury biomechanics expert, to review the case. Both concluded the child -- found unresponsive on the first floor of his father's home -- was beaten and then forced over the balcony either against his will or in a desperate attempt to escape his assailant.

"I can't imagine anyone in the world wanting to harm Maxie," Shacknai told FoxNews.com. "He was the most sweet, loving and gentle boy."

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The circumstances surrounding the child's death were bizarre from the beginning.

Shacknai's girlfriend, 32-year-old Rebecca Zahau, was watching the boy along with her 13-year-old sister when the incident occurred on July 11, 2011. Jonah Shacknai, 53, was not home at the time. Zahau told investigators that she was in the bathroom when she heard a loud noise and then found the boy lying on the first floor with broken pieces of a chandelier beside him.

In a strange turn of events, Zahau was found hanging by her neck --  naked with her hands and feet bound -- from an outdoor balcony at the mansion two days later. San Diego County investigators ruled her death a suicide – claiming she was grief-stricken over the boy's grave condition  – but Zahau’s family maintains she was killed.

Max died at Rady Children’s Hospital in San Diego four days after Zahau was found hanging at the home and a week after his fall from the balcony.

A report by the San Diego County medical examiner's office ruled that the manner of his death was accidental. But Dina Shacknai said doctors treating Max were immediately suspicious of his injuries and contacted Child Protective Services, which she said launched a probe and then dropped it once the medical examiner ruled the death an accident.

Melinek told FoxNews.com that the child had injuries to his body that could not have been caused from a fall alone. She also said it was impossible for the child to have accidentally bumped into the balcony and then fallen over.

"It doesn't make any sense. It defies gravity," Melinek said of the scenario presented by Coronado police working in collaboration with Dr. Mark A. Gomez, who authored the first report in the case. "He’s got too much injury for just a simple fall from the railing," she said, adding that the boy's center of gravity was too low for him to have flipped over the banister on his own.

"I do not disagree with the coroner's determination that the cause of death was due to blunt force trauma," Melinek said. "What I did disagree with was the manner of death, which I believe was a homicide."

"The fall alone ... would not account for the abrasions and contusions along the right forehead, inner eye and lids, the left ala, or the right shoulder and neck," the report reads. "The more planes of injury ... the more likely that an incident is the result of an assault rather than a simple or even complex fall."

"The nature and location of Max's skull fracture and subgaleal contusion are indicative of a head-first contact with the first floor surface and thus are consistent with Max moving or being moved over the railing following the assault causing him to fall to the first floor,"

A spokeswoman for the San Diego medical examiner's office was not immediately available when contacted Tuesday. Ben Metcalf, a public information officer at Rady Children’s Hospital, said officials there are prohibited from discussing the case due to privacy laws.

Lea Corbin, a spokeswoman for the Coronado Police Department, said authorities are planning to review the report by Melinek and Bove. After doing so, she said, investigators will decide whether to reopen the investigation.

Dina Shacknai, meanwhile, is confident that they will.

"We have provided them real science and our experts' reports are based on science," Shacknai told FoxNews.com. "It couldn’t have happened the way they said. He [Max] couldn’t have gone over that banister on his own."