However, O'Malley said her office's probe into the collapse of the fourth-floor balcony during a party at the Library Gardens apartment complex at 2020 Kittredge St. at 12:41 a.m. on June 16 is just getting started so it is far too early to know what it will find.
PHOTOS: Several killed in balcony collapse in Berkeley
Of the six people killed, five were Irish nationals -- Olivia Burke, Eoghan Culligan, Niccolai Schuster, Lorcan Miller and Eimear Walsh. The sixth victim was 22-year-old Rohnert Park resident Ashley Donohoe.
Speaking at a crowded news conference in her office, O'Malley promised that her office will conduct "a through and exhaustive investigation" and "look at every aspect from every angle," but said she won't file charges if there's not enough evidence to support them.
"We will find out if there are facts that support criminal charges and if they can be proved beyond a reasonable doubt in a court of law," O'Malley said.
Alameda County's top prosecutor declined to be specific about the targets of her investigation, such as whether it includes the people and businesses who built, owned, managed or maintained the apartment complex.
But O'Malley said a key focus of the investigation is whether there was criminal negligence by those responsible for the building.
She said factors the probe will look at are whether there was more than ordinary carelessness, inattention and lack of judgment and whether those factors created a high risk of death or great bodily injury.
A civil prosecution on consumer protection issues is also possible if the investigation doesn't produce enough evidence for a criminal prosecution, O'Malley said.
The balcony that collapsed was left hanging straight down along the building face and has since been removed. Berkeley city officials also ordered the removal of the balcony one floor below the collapsed balcony because it was damaged and they said it posed a public safety risk.
O'Malley said the collapsed balcony is in the custody of the Berkeley Police Department at "a protected place" she declined to disclose and the balcony underneath that was removed is being moved to "a secure location" that will be guarded by the Alameda County Sheriff's Office.
Berkeley city officials said on Tuesday that their investigation found that the balcony was supported by wooden beams that had been badly rotted by water damage.
The city's investigation didn't consider potential criminal negligence and instead focused on regulatory reforms such as imposing more stringent requirements for building and inspecting outdoor balconies.
O'Malley said the city's probe was limited in scope and her office will conduct a wider investigation that will include forensic and laboratory analysis.
She said her office has many investigators who are knowledgeable about building issues but she also will bring in "the best experts" from state government and other outside agencies.
O'Malley said the Berkeley Police Department will work with the district attorney's office in the investigation.
"We want to move forward as expeditiously as we can," she said, but added she has no estimate of how long it will take to complete the investigation.
O'Malley said the statute of limitation for involuntary manslaughter is three years so her office theoretically has that amount of time to finish its probe and bring charges.
Click here to find out how you can support the Irish students currently in Berkeley during this difficult time.
Click here for a GoFundMe account for families of the Berkeley balcony collapse.
ABC7 News Reporter Janet O contributed to this story.