CORONADO, Calif. (CBS 8) - Sheriff investigators confirmed Wednesday the presence of unidentified, mixed DNA samples found at Coronado's Spreckels mansion where Rebecca Zahau, 32, was reportedly found hanged to death.
Zahau family attorney Anne Bremner first revealed that mixed DNA was found at the death scene during the airing of the Dr. Phil Show earlier this week.
"We have mixed DNA in this case all over, in things like the knife, the bed frame, black gloves," said Bremner on the syndicated television talk show. "Mixed DNA unexplained as to who these other donors are."
"It's a case that just cries out for answers and investigation. We have mixed DNA in her fingernails," the Seattle-based attorney said.
The significance of the DNA findings was debated during a hastily-organized news conference Wednesday afternoon, held in response to the findings from a second autopsy performed on Zahau's body and discussed on the Dr. Phil program.
Sheriff's Crime Lab Director Michael Grubb did not dispute the presence of unidentifiable, mixed DNA at the Coronado scene.
"The majority of the DNA under Rebecca Zahau's fingernails was her own," said Grubb. "Various fingernails were tested as separate samples and one of them showed a DNA mixture but the level of DNA was so low that it was an un-interpretable mixture."
In addition to the fingernail sample, unidentified DNA also was recovered from the rope used in Zahau's alleged hanging; a large knife used to the cut the rope; the bed frame to which the rope was tied; a door knob on the balcony door; and a pair of black gloves found on a table in the mansion, Grubb said.
"DNA can come to be on all sorts of surfaces; door knobs, any public surface can gain DNA from a number of people and it will reside there and may be picked up by someone else," said Grubb. "When you have a low-level mixture and it's so low that it's un-interpretable, it means that even if we have other subjects to compare, it's not going to be fruitful."
Because the amount of mixed DNA recovered was so minuscule, San Diego County Sheriff Bill Gore said it was unnecessary to collect DNA samples from Zahau's boyfriend, Arizona tycoon Jonah Shacknai, or Jonah's ex-wife, Dina Shacknai.
Jonah and Dina are the parents of Max Shacknai, 6, who was on life support at Rady Children's Hospital on the night Zahau died, following a fall down the mansion staircase July 11.
Detectives concluded both parents were also at the hospital that night and into the morning of July 13, when the body of Zahau was discovered.
"We knew where Jonah (Shacknai) was," said Sheriff Gore. "If we had come up with unknown DNA during the course of our investigation we could have taken DNA samples from Jonah."
Attorney Bremner said Jonah Shacknai is seen on hospital surveillance video on the night of Zahau's death, but Dina Shacknai is not.
Sheriff Gore confirmed as much during his news conference.
"We don't have her (Dina Shacknai) on surveillance tape," Gore confirmed. "Her position was determined thorough GPS triangulation on her cell phone, which put her in the vicinity of Rady Children's Hospital."
After a seven-week investigation, detectives concluded Zahau committed suicide by hanging because she received bad news that Max Shacknai would not survive his injuries. Zahau was babysitting the boy when he was injured.
Zahau's family maintains she was murdered and the suicide scene was staged.
On the Dr. Phil program, Bremner questioned why underwear found inside a bedroom at the mansion guest house was never tested for DNA.
Jonah Shacknai's brother, Adam Shacknai, had stayed in the guest house overnight and called 911 in the morning to report he had found Zahau hanging.
"They didn't look at a pair of woman's underwear in a garbage can in the guest house," said Bremner. "The underwear was not analyzed."
Sheriff Gore said it was not necessary to test the underwear, based on his department's investigation and statements made by Jonah Shacknai.
"In the case of the underwear, it was determined through investigators that Jonah Shacknai's daughter, Gabby, and her girlfriends had stayed in the guest house up to a week before," Gore said. "It did not appear to be relevant to our investigation and not everything we seize in a crime scene is eventually submitted for forensic examination."
Grubb, the crime lab director, also was questioned about the underwear during the news conference.
"The underwear was collected but was not examined because of Jonah Shacknai's statement and the fact that we had better evidence as to whether Rebecca Zahau was sexually assaulted or not; and that was her body – and swabs recovered from her body – which showed no sexual assault," responded Grubb.
Similar questions were raised about a spot of blood found in a bathroom shower near the death-scene bedroom. The blood was never tested for DNA because detectives believed it was menstrual blood from Zahau.
"There was blood found on Rebecca's body, which was determined to be menstrual blood. There was also blood spotting on the floor, on the carpet, and a small spot in the shower," Gore explained.
The blood spots on the carpet and on Zahau's body did undergo DNA testing and were identified as her own menstrual blood; therefore, said Gore, the blood spot in the shower also was determined to be her own blood, "through logical investigative work."
"To take every little piece and look at the shower blood, we just don't do that," Gore concluded.