(CNN) Chris Cornell's doctor is to blame for the Soundgarden singer's death, his family states in a lawsuit filed Thursday.

Dr. Robert Koblin "negligently and repeatedly" prescribed "dangerous mind-altering controlled substances" that impaired Cornell and "caused him to engage in dangerous impulsive behaviors that he was unable to control, costing him his life," according to the lawsuit obtained by CNN.

The lawsuit was filed in Los Angeles Superior Court.

Chris and Vicky Cornell in 2012

The rock star had a history of substance abuse and chemical dependency. His family claims that Koblin prescribed Cornell more than 940 doses of lorazepam (also known as Ativan) during the last 20 months of his life.

"Yet, at no time during this period did Dr. Koblin conduct a medical examination of Mr. Cornell, perform any laboratory studies, obtain an interim history or do any type of clinical assessment of Mr. Cornell," the suit states.

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