Dan Jansen recently started talking for the first time in more than a month.

The 57-year-old has a large crater in his head from where doctors removed part of his skull and brain, following an altercation with a group of skateboarders in San Francisco in November.

He still can’t stand up on his own, and it’s unclear if Jansen, who was living in Pacifica, even recognizes his family, who keep vigil with daily visits to his hospital bedside.

But as the family watches his agonizingly slow recovery, they are also following the criminal case against his alleged attacker, 24-year-old professional skateboarder Jesse Vieira.

“This has been devastating,” said Jansen’s niece, Amanda Jansen. “You want to help, but you feel powerless. There’s only so much you can do, and our primary concern is his well-being.”

She was among more than a dozen supporters wearing red T-shirts with the words “Justice for Dan Jansen” across the front at Vieira’s hearing Friday in San Francisco Superior Court.

Attorneys argued whether the defendant should be granted bail before his trial on felony charges of assault with a deadly weapon, assault with force likely to commit great bodily injury, and battery with serious bodily injury.

Judge Teresa Caffese ordered Vieira, whose hometown is Stockton, to be held without bail.

The courtroom was also packed with supporters of the slightly built Vieira, who said nothing as he stood in his orange jail-issued clothing. “Love you Jesse!” two people called from the gallery as Vieira was taken back to jail.

The emotionally-charged case will likely come down to whether a judge or trial jury believes Vieira was acting in self-defense during the Nov. 25 encounter.

Jansen, a former Army soldier, was working as a security guard at the plaza outside the Bank of America center at 555 California St. in the city’s Financial District. Vieira and others were skateboarding on the plaza around 3:30 p.m., prompting Jansen to kick them out, prosecutors said.

When the skateboarders wouldn’t leave, Jansen put up barricades, which some in the group knocked down. An altercation erupted and Vieira smashed Jansen in the head with his skateboard, knocking him to the ground and causing his brain to bleed and swell, prosecutors said.

The episode was captured by a security camera across the street, leading investigators to identify Vieira. Police arrested him after executing a search warrant on Dec. 10 at his home, where they found “clothing worn by defendant as depicted in the video,” Assistant District Attorney Kimberly Williams wrote in court papers.

But Doug Rappaport, Vieira’s defense attorney, said in court Friday that he has evidence that proves his client was defending himself in the incident.

Video taken by a skateboarder from inside the fracas, he said, shows another man initially striking Jansen, who fell to the ground. Jansen then got up and started throwing punches at Vieira, Rappaport said.

Vieira defended himself, first swinging his skateboard toward Jansen before the two exchanged punches and Jansen fell to the ground unconscious, Rappaport said.

“Jesse was only defending himself here,” he said. “The security guard fell to the ground and hit his head,” he said. “It’s tragic for everybody. But for the second video, an innocent kid would be doing a lot of time.”

Judge Coffese disagreed with Rappaport’s assessment, saying Vieira “chose to interact and assault the victim and then give a statement that he wasn’t involved.”

Paramedics rushed Jansen to San Francisco General Hospital, where he was put into a medically induced coma as his brain swelled. Doctors removed a portion of his skull to relieve pressure and later cut out a section of the right hemisphere of his brain.

Two weeks later, he began to regain consciousness. He still can’t walk or stand on his own, and he needs to be helped out of bed and into a wheelchair by a crane-like contraption attached to the celling, Amanda Jansen said.

His family, though, has begun to see some improvements. Jansen can talk a little. He can feed himself. He can brush his teeth. He may not know who his family is, but he has recognized a few of his co-workers.

Before the injury, Jansen was an avid fisherman who kept a YouTube channel under the name Pacifica Fisherman, where he teaches techniques on fishing and preparing things like perch, cod and crab.

His family knows he’ll never be the same, but they hope one day he will be able to retire and get back to his passion for the ocean.

“I really just count my blessings and remind everyone around me to enjoy everything around them now, because you never know when it’s going to be gone,” Amanda Jansen said.

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky