MARTINEZ (CBS/AP) — A judge has ordered a Concord man to stand trial on charges of involuntary manslaughter in the fatal mauling of his 2-year-old step-grandson by pit bulls.

Contra Costa County Judge Clare Maier on Thursday decided to increase the charges against 53-year-old Steven Hayashi from felony child abuse and owning a mischievous animal that caused death to involuntary manslaughter. She issued the ruling at the conclusion of Hayashi’s preliminary hearing.

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But Maier rejected prosecutors’ request that Hayashi be charged with second-degree murder in his grandson, Jacob Bisbee’s, July 2010 death.

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Authorities said Hayashi was not at home when Bisbee was attacked by at least three pit bulls in Hayashi’s garage. The boy had been left unsupervised.

Hayashi’s attorney has argued that Jacob’s father is to blame because he did not arrange for child care.

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