SACRAMENTO (CBS13) — A brutal crime in South Sacramento was caught on video, which shows a man with autism being attacked from behind.

For decades, Stephen Chapman, better known as “Stevo,” has had the same routine: Get off work at UC Davis Medical Center at 1 p.m., take the 51 bus and walk a couple of blocks home.

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“He has a very strict routine that’s also because of his autism,” explained Tina Chapman, Stephen’s sister-in-law. “Everything is done at a certain time every day.”

Wednesday, his schedule was interrupted while he was walking near Stockton Boulevard and Fruitridge Road. Video of the attack shows a person dressed in all black running up behind Stephen and hitting him in the head, knocking him down to the ground.

“His head literally bounced off the sidewalk,” Tina said.

As Stephen struggled to get up, the attacker punched him for the second time.

“I didn’t know what to think. The first thing I thought is ‘Why, why would someone do this to him?” questioned Tina.

The dashcam video ends when Maria Valencia gets out of her car to step in.

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“The first time, you are in shock, and she went after him a second time and that’s when I said ‘Hey, hey, no, no, stop’ and she came at me,” she said.

Maria believes the attacker was a woman. The person eventually walked away as witnesses called the police.

“You have to help people that are helpless themselves. He didn’t fight,” said Maria.

The beating left the 53-year-old black and blue, with bruises to both of his eyes, a lump on his head and a couple of cuts to his face.

Stephen said he is afraid to walk home alone after the beating.

“He has the same question why, why did this happen to me and I don’t know what to tell him. what do I say to him? He doesn’t comprehend that people are bad because he is a good spirit,” Tina explained.

Stephen’s family plans to drive him to and from work in the future.

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“I just don’t feel like it’s safe anymore for him to be out there,” Tina said.