After a nine-month investigation, the Alameda County District Attorney’s Office announced it would not file criminal charges in connection with the Berkeley balcony collapse in June 2015, which killed six and injured seven.

The office announced Tuesday that there is insufficient evidence to bring criminal manslaughter charges against any one individual or company, despite concluding that “the responsibility for this failure likely extends to many of the parties involved in the construction or maintenance of the building,” according to a statement from the office Tuesday.

The decision comes after a team of investigators and prosecutors reviewed all known evidence, interviewed witnesses and experts and conducted an in-depth legal analysis aided by several state agencies.

“I am keenly aware of the devastation and injuries each victim and each family suffered and continues to confront,” said District Attorney Nancy O’Malley in a statement.

The collapse impacted communities both at home and abroad in Ireland, with five Irish students and one California student killed in the incident, and prompted swift responses from city officials, local engineers and legal experts to prevent future collapses.

“This is not a decision that I came to lightly,” O’Malley said in the statement.

The office announced in June 2015 that it would conduct an independent investigation into the cause of the collapse, after the city planning and development department announced that forensic examination and laboratory tests of the balcony were outside the scope of its review.

“The duty fell to us to investigate further to determine whether or not criminal conduct was at play,” said Alameda County assistant district attorney Teresa Drenick. “We felt it was that important, and we’ve worked really hard for nine solid months.”

Filing a manslaughter case based on criminal negligence would require the district attorney to determine that any defendant or defendants acted with “reckless conduct akin to a disregard for human life” and that the deaths resulting from those actions were reasonably foreseeable, the statement read.

Berkeley Mayor Tom Bates said in a statement Tuesday that he is not surprised by the district attorney’s office’s decision not to file criminal charges.

“Nevertheless I am optimistic that the safeguards we have adopted in Berkeley in the wake of the balcony collapse … will help us make sure that such a tragedy doesn’t happen again,” Bates said in the statement.

In July 2014, City Council passed new city ordinances effective immediately requiring weather-exposed structures to be inspected every three years, with mandatory inspections for all city balconies within six months of the building codes’ implementation.

Of the more than 6,000 buildings inspected, almost 20 percent of properties required corrective work, according to a city report released in February.

“I hope for a speedy and just resolution of the civil court action pending on their behalf,” Bates said in the statement regarding the surviving victims and families and friends of the students killed in the balcony collapse.

In November, families of the balcony collapse victims filed a total of 13 lawsuits against the construction firm responsible for building the balcony, in addition to the building’s owner and manager, alleging they ignored signs that the balcony was unsafe and cut corners to save money.

According to Drenick, the criminal court system is separate from the civil court system, where the ongoing lawsuits will be handled.

In a statement from Rains Lucia Stern — the law firm representing one of the families of a victim killed in the collapse — the Donohoe family hoped criminal charges would be pursued and is disappointed in the office’s ultimate decision.

“There is a deep desire for this case to act as a lesson for other builders and avoid a tragedy like this from happening again,” the Donohoe family’s statement read.

Findings from the investigation appear to establish the culpability, the statement from the Donohoe family reads, of many of the defendants in the family’s pending civil lawsuit.

In addition to reviewing building plans and inspection and maintenance records, the investigation included destructive testing of the property’s balconies, leading to the determination that dry rot was the primary cause of the collapse.

The district attorney’s office will work with the California Contractors State License Board in any administrative action the board pursues against the involved construction companies, according to the office’s statement.

Additionally, the office plans to collaborate with state legislators and industry leaders to consider amending building codes and inspection oversight laws.