BERKELEY (CBS SF) – The Alameda County District Attorney’s office announced Tuesday that no criminal charges will be filed in connection with a balcony collapse that killed six students in Berkeley last year.

After months of investigation, the DA’s office believes the primary reason behind the collapse is that water that was trapped in the balcony deck when it was constructed, leading to dry rot damage.

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“This is not a decision that I came to lightly,” District Attorney Nancy O’Malley said.  “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.”

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The collapse took place at the Library Gardens Apartment Complex on Kittredge Street on the morning of June 16th, 2015. Students were celebrating a 21st birthday party when the balcony collapsed shortly after 1 a.m.

Six students, five of whom were visiting from Ireland for the summer, were killed. Seven people were also injured in the collapse.

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Meanwhile, civil litigation connected to the balcony collapse continues. Survivors and family members have filed 12 separate lawsuits against the owners, managers and builders of the apartment complex.