PITTSBURGH (KDKA) — A mother is still in shock after her son was stabbed and killed in Pittsburgh.

On Monday, Pittsburgh police say they arrested Melvin Banks in connection to three stabbings in the Lincoln-Lemington area.

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One of those victims was Greg Walker, who died Saturday.

“I just can’t believe he’s not here. I don’t believe it,” Christine Walker told KDKA’s Jennifer Borrasso. “Greg was a very kind and warm, loving and giving person. He would never harm a fly. He would do anything for you.”

Christine is still in shock after her 37-year-old son was stabbed to death by a stranger. The family has set up a GoFundMe page, which can be found here.

She said Greg was mentally disabled and recently started living with his sister.

(Photo Credit: Provided)

The night he was stabbed, he left the house looking for cigarette butts.

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The family says he had no money, only a cell phone with him.

“He was just wandering like he always does,” Christine said.

But Greg never made it home, and police say he was stabbed multiple times near the intersection of Lincoln Avenue and Wiltsie Street, where police say he died.

“I don’t know why this guy would just come up to him and stab him in the face. It just makes me sick,” Christine said.

Now all she can do is hope for justice.

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“I just love him and I miss him. And I hope he’s with my mom and his dad, and God is holding him right now,” Christine said.