One day after the Los Angeles Police Department announced a suspect had been arrested in the near-fatal beating of a San Francisco Giants baseball fan outside Dodger Stadium, a doctor involved in his treatment said there was no change in his condition.

Bryan Stow, a 42-year-old paramedic and father of two, has been in critical condition since the March 31 beating that left him with brain damage.

Stow was initially treated in L.A., where doctors put him in a medically-induced coma to prevent seizures. Then he was transferred to San Francisco, where doctors last week reported that Stow has been able to open his eyes.

On Monday, however, San Francisco General Hospital spokesperson Rachel Kagan said little had changed in his condition.

"Brian Stow's condition is still the same as it was reported to you on Wednesday, May 18," Kagan told reporters.

"He is here in critical condition, he is stable, he is undergoing continuous monitoring and comprehensive assessment."

Stow's horrific beating, apparently for wearing a Giants' jersey to the Dodgers home opener, sparked outrage in the sports world and beyond.

He was with two friends and had just texted a family member to say he feared for his safety in the boisterous post-game crowd, when the attack occurred.

On Sunday, the LAPD announced they had arrested a suspect in the beating, 31-year-old Giovanni Ramirez, after receiving a tip from a parole officer.

Police said Ramirez was nabbed in an early morning raid in East Hollywood and was believed to be the "primary aggressor" in the attack.

Ramirez was charged with assault with a deadly weapon.

Police are still seeking additional suspects.

On Monday, speaking at the news conference, Stow's sister Erin Collins praised the LAPD for "exhaustive efforts regarding Bryan's assault."

"We never gave up hope that this day would come, that the beginning of justice being served would happen," Collins told reporters.

"We look forward to the day the other suspects are apprehended."

Collins also said her brother's plight is difficult for the family, but relatives are speaking to him and playing music for him daily, hoping that he understands what is taking place.

"Bryan has a long road ahead of him but we are thankful the suspect is in custody and is unable to do this to another family," she said.

LAPD Chief Charlie Beck said on Sunday that 20 full-time detectives have been working on the case, following up on some 630 leads.

Ramirez was one of several suspects detained by police after warrants were served on two homes early Sunday morning.

Ramirez was one of two suspects wanted in the beating, along with a woman who drove them from the scene of the attack.

Beck said Ramirez's appearance had become familiar to many in Southern California due to flyers and billboards featuring sketches based on witnesses' descriptions.

Ramirez was described as having a bald head, goatee and tattoos. Both Ramirez and the other suspect were wearing Dodger jerseys.

Rewards totalling US$200,000 had been offered for information leading to an arrest.