ELK GROVE (CBS13) – After two months of heartbreak and questions, the Smith family finally has some answers.

Berkeley police arrested 60-year-old tony Lorenzo Walker in the shooting death of 19-year-old Seth Smith. Smith was shot in the back of the head while out walking in his Berkeley neighborhood in June.

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“I’m calmer knowing that we know that someone would be behaving in this horrific way is off the street,” said Smith’s mom Michelle.

Michelle Smith is feeling some relief, but the heavy question still lingering: why would anyone do this to her son, a young college student simply out for a walk?

“My son’s never met this person. They had no altercations, paths that crossed, it’s truly heartbreaking,” Smith said.

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“Damn it you’ve got to care. This is a young boy’s life and you’ve got to care,” said Kelley Scarsbrook.

The Roseville mom started a petition demanding justice for Seth after reading about his story on social media. From one mom to another she wanted to show her support for the Smith family and get Seth’s killer off the street.

“If this could happen to Seth, simply out for an evening walk, then it could happen to any of them,” said Scarsbrook.

“There’s this very big open space that feels empty until we fill it with the facts but then there will always be that additional empty space for where Seth belonged in our family,” said Smith.

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Walker is set to be arraigned on Tuesday, Aug. 25.