By CBSNewYork Team

NEW YORK (CBSNewYork) — New video shows a man brutally attacked in the Bronx.

Police say the victim was ambushed from behind and struck on the back of the head with a cobblestone. The attacker then stomped on him.

READ MORE: Mother, 12-Year-Old Daughter Killed In Queens Car Crash

The victim’s sister spoke to CBS2’s Christina Fan.

“We went to the hospital, and we saw him in the bed with stitches, and his head was, like, swollen,” 24-year-old Yaniris Marte said.

She told Fan she was the one who retraced her brother’s steps, and found the shocking surveillance footage of the attack.

“I stayed there for, like, four hours. I said, ‘I’m not leaving. I have to see something.’ I’m still like, what happened?” she said.

A man is in critical condition after a brutal beating caught on video in the Bronx. (Credit: NYPD)

She’s determined to get justice for her older brother, who can be seen on surveillance video being viciously beaten, shoved, and kicked to the point of unconsciousness.

“They didn’t even give him a chance to defend himself. That’s what makes me mad looking at the video,” she said.

She says her 28-year-old brother Franklin Marte suffers from sickle cell anemia and was on his way home from the hospital the morning of June 9th when a man attacked him from behind on Brook Avenue in the Bronx.

The suspect first struck him with a cobblestone, stomped on his head, then picked up a different stone and hit him again.

READ MORE: 'God Is Not Sleeping': Grief-Stricken Family Calls For Suspect In Deadly Long Island Stabbing To Turn Himself In

“In the video, it doesn’t seem like he took nothing. He was trying to kill my brother. Not fight him, just kill him,” Yaniris Marte said.

Franklin suffered severe head trauma and was rushed to Lincoln Hospital in critical condition.

His family shared video of his slow but steady improvement. They say he has regained some movement in his hands and legs. He needed 59 stitches and is still unable to speak.

“He’s going to need therapy, and his mood is going to change. He’s probably going to be mad, happy. And we just got to understand,” Yaniris Marte said.

Police are asking for help to identify the suspect, seen in videos with a hoodie over his head.

Yaniris says her family visits her brother daily and hope to be able to tell him soon that officers found his attacker.

“I would tell my brother keep fighting, that I’ve got him, I’m going to find out who did this to you, he’s going to get locked up and you don’t have to be scared,” she said.

Anyone with information about the attack is asked to call the NYPD’s Crime Stoppers hotline at 1-800-577-TIPS (8477), or for Spanish, 1-888-57-PISTA (74782). You can also submit a tip via their website or on Twitter, @NYPDTips. All calls are kept confidential.

MORE NEWS: Jackie Mason, Comic Who Perfected Amused Outrage, Dies At 93

Christina Fan contributed to this report.

CBSNewYork Team