No criminal charges will be brought over the Berkeley balcony collapse that killed five Dublin J1 visa students and an Irish-American woman last summer, the US district attorney who investigated the tragedy has said.

Alameda County district attorney Nancy O’Malley, who prosecutes crime in the San Francisco Bay Area city in northern California, concluded after a nine-month investigation that there was not enough evidence to bring criminal charges.

The prosecutor’s office found after considering the evidence and expert legal analysis and opinion that “there is insufficient evidence to bring criminal manslaughter charges against any one individual or company”.

“This is not a decision that I came to lightly,” she said in a statement.

“It is the culmination of months of consultation with my team of attorneys. It follows extensive review of reports, both legal and factual, and numerous meetings with investigators and experts.”

Students Olivia Burke, Eoghan Culligan, Lorcán Miller, Niccolai (Nick) Schuster and Eimear Walsh, all 21 years old, and Ms Burke’s cousin Ashley Donohoe, 22, of Rohnert Park, California, died when the fourth-floor balcony they were standing on collapsed during a 21st birthday party in the early hours of June 16th, 2015.

Another seven Irish students - Aoife Beary, Clodagh Cogley, Sean Fahey, Conor Flynn, Jack Halpin, Niall Murray and Hannah Waters - who were also on the balcony, were injured in the tragedy at the Library Gardens apartment block on Kittredge Street in downtown Berkeley when they fell 12 metres to the street below.

Letters to families

Ms O’Malley wrote letters to each of the families over the weekend informing them of her decision prior to it being announced publicly by her office.

“Not a day has passed since the tragedy of June 16 that I have not thought of the victims and their families,” she said.

“I am keenly aware of the devastation and injuries each victim and each family suffered and continues to confront. Friends, families and entire communities both in California and in Ireland have been affected by the horror of that day.”

Ms O’Malley’s office said experts working for her investigators believe the primary cause of the collapse was water being trapped or “encapsulated” in the balcony during the construction in 2005 and 2006, leading to extensive dry rot damage.

“There appear to be many contributory causes of this encapsulation, including the types of material that were used (none of which are prohibited by the building code) and the very wet weather Berkeley experienced during the months of construction,” the DA’s office said.

“The responsibility for this failure likely extends to many of the parties involved in the construction or maintenance of the building.”

Her office said that to file a manslaughter case based on criminal negligence, she must be satisfied that any defendant or defendants “acted with gross or reckless conduct to a disregard for human life and the deadly consequences of those actions were reasonably foreseeable”.

Reasonable doubt

“Any such charges would have to be proved beyond a reasonable doubt to 12 impartial jurors, all of whom must unanimously agree,” the office said.

Having considered all the known evidence and conducted “an in-depth legal analysis based on expert opinion”, the DA concluded there was insufficient evidence to be able to bring such criminal charges.

Lawyers for 12 of the Berkeley families said most legal experts did not expect criminal charges, given the high burden of proof and the likelihood that more than one person’s misconduct over a 10-year period caused the collapse.

They said the investigation by the district attorney’s office would benefit the civil legal actions for damages taken by the families of the six victims and the seven survivors in the Californian courts.

“It remains our clients’ quest to uncover the truth, to hold those responsible accountable and to bring about changes to industry practices to prevent such a needless tragedy from recurring,” said attorneys Matthew Davis and Richard Schoenberger of San Francisco firm Walkup, Melodia, Kelly & Schoenberger, which represents all the Berkeley families except the family of Ashley Donohoe.

The Berkeley families have taken legal cases against Segue Construction, the California contractor that built the apartment block, the property’s owner, a subsidiary of asset management giant Blackrock, and about 30 other companies involved in the construction, design and maintenance of the property.

Ms O’Malley’s office said it would continue to work with the California Contractors State Licence Board in any administrative action it pursues against firms involved in the building’s construction.

It also plans to collaborate with industry leaders and state legislators to consider amending building codes and inspection oversight laws “so that tragedies like this never occur again”, her office said.

The district attorney retained a variety of outside industry experts to assist in her criminal investigation, including in the “destructive testing” of the building, the collapsed balcony and a second balcony removed from the floor below.

The family of Ms Donohoe said they were “disappointed” that criminal charged are not being pursued but are “very appreciative” of the work carried out by the district attorney when others would not carry out a criminal investigation.

Speaking through their lawyers, San Francisco firm Rains Lucia Stern, the family of the California student said the decision not to bring criminal charges shows how it was “very difficult” to prosecute a corporation over such a tragedy.

“Their feeling is that the whole concept of the criminal law is supposed to act as a deterrent and the most important thing to them is that something like this doesn’t happen again,” said the firm in a statement.

The attorneys said the Donohoe family’s fear was “that if there is no deterrent, there will continue to be similar types of accidents that will occur in the future”.

Flanagan response

On Tuesday afternoon, Minister for Foreign Affairs Charlie Flanagan responded to the announcement regarding criminal charges in the matter not being brought. “My department will carefully consider the details of the District Attorney’s findings,” his statement said.

“While the District Attorney’s investigation did not find sufficient proof to take separate criminal proceedings, it has shone a vital light on the circumstances and factors that contributed directly and indirectly to the collapse of the balcony.

“This investigation is an important step in a process, the ultimate objective of which is to ensure that a tragedy such as Berkeley never occurs again.

“My department remains in close contact with the families and will continue, including through our Consulate General in San Francisco, to offer them our full support and assistance.”

Previous collapse case

San Francisco district attorney Terence Hallinan brought manslaughter charges against a landlord over a fatal balcony collapse in 1996, though the landlord was ultimately convicted on lower misdemeanour charges and avoided prison.

Regarding today’s decision, mayor of Berkeley Tom Bates told The Irish Times: “I can’t say I’m surprised because it was always difficult to reach a legal threshold to bring a manslaughter charge case. I knew it was going to be an uphill battle.”

He said he hoped the California Contractors State License Board would introduce stricter requirements on inspections and building standards following similar changes made by the City of Berkeley in the aftermath of the tragedy.