Police arrested 31-year-old Giovanni Ramirez as their prime suspect, but he has not been charged. Ramirez was placed in a police lineup at the Men's Central Jail on Wednesday to see if witnesses could single him out.
Beck said the lineup "went well," but offered no further details.
"I think it would be premature and really not fair to either side for us to tell you what happened at the lineup, so we all agreed that nothing else is going to be said," said Ramirez's attorney, Anthony Brooklier. "I will say this: I think that LAPD bent over backwards to give us a fair lineup."
Beck had a much more somber tone during the news conference than on Sunday, when the arrest was announced. But the chief stressed that Ramirez remains the top suspect in the case.
"Giovanni Ramirez is and was and has been our primary suspect on the Stow beating. We continue down that road in our preparation of presenting a case to the district attorney in the near future," Beck said.
Ramirez is in custody on a parole hold. No charges have been filed against him.
"I am as sure as you need to be to make an arrest and pursue a prosecution," said Beck.
Stow, 42, was attacked by two men in the Dodger Stadium parking lot on March 31. The beating left Stow with a severe skull fracture, and he remains in critical but stable condition at a San Francisco hospital.
Brooklier insists that his client is innocent and was never at Dodger Stadium at the time of the attack. He says Ramirez was at home in East Hollywood babysitting.
"We're going to do what we can to show the district attorney's office that we have an innocent client. Not just that they can't prove it, but that we have an actually innocent client," Brooklier said.
"I'm not surprised he has an alibi. Defense attorneys are going to try to make their case. Our prosecutors will make ours," said Mayor Antonio Villaraigosa.
Beck said police have other evidence against Ramirez. He said detectives are still sifting through 700 clues that have come in from the public.
Police have not yet identified a second attacker and a woman suspected of driving the pair from the scene. Anyone with information about the case is urged to call (877) LAPD-24-7.