The LAPD said it is "satisified" after placing the suspect in the beating of Giants fan Bryan Stow in a lineup for potential witnesses.
The suspect, Giovanni Ramirez, was arrested Sunday.
On Tuesday, prosecutors met with Los Angeles police detectives to review the case and determined that more investigating needs to be done before charges can be filed.
"Following the rules and guidelines established for the procedure, the department is satisfied with the results," the department said in a statement after the lineup Wednesday night. "At the appropriate time detectives will present a case to the Los Angeles County district attorney’s office. Ramirez remains in custody on a parole hold by the California Department of Corrections."
Typically, suspects must be charged within 48 hours of an arrest, but in this case Ramirez, 31, is in custody on an alleged parole violation. Ramirez was arrested in connection with the beating of Stow at Dodger Stadium after the team's season opener.
Police said Ramirez was staying at a different apartment than the one he had registered with parole officials, a potential violation of the terms of his release.
The sources, who requested anonymity because the investigation is ongoing, said the parole hold has given investigators flexibility to conduct more work before formally presenting the case to the district attorney's office. They stressed that the decision to conduct additional investigation was not a reflection on the strength or weakness of the evidence against Ramirez and said such a move is routine when suspects remain behind bars on unrelated matters.
They declined to specify what additional investigation needed to be done, saying they wanted to avoid jeopardizing the case.
A lawyer representing Ramirez's 10-year-old daughter said Wednesday that at least eight people -- including the daughter -- could corroborate his alibi that he was at an East Hollywood apartment the entire day.