Trutanich addressed the city council Tuesday announcing a probe into the approval of $1.4 million in police, overtime, and other payments related to the event.
"Our investigation has taken an unanticipated turn that raises both civil and criminal aspects," Trutanich told the city council. "Ethical considerations and the need to protect the integrity of the investigation prevent me from discussing anything related to the criminal investigation."
Trutanich then held a closed-door session with city council members, who would not discuss the city's investigation.
"I am not going to discuss anything regarding the city attorney," said L.A. City Councilman Dennis Zine. "The city attorney made a comment and went into closed session. That is a confidential meeting that we conducted and I'm not going to go into detail or respond to any questions regarding that."
Council members want to know who made the crowd estimates, who authorized all the police and personnel for the event, and where all the money went. The city council is seeking a full accounting of city resources used and money spent in response to the public reaction to the 50-year-old singer's death.
"We look at this massive expenditure of resources, personnel in all departments, not only police and the fire and street services, but many departments were involved in this," said Councilman Zine. "We need to analyze and figure out how this happened, who authorized, why was it authorized, and where do we come up with the inflated numbers because we didn't have a half-million people show up at the memorial."
The mayor's office says the city had to pay about $1.4 million, but Councilman Zine believes it is closer to $3.9 million.
Some officials, including Zine and Councilwoman Janice Hahn, say concert promoter and Staples Center owner AEG will make millions off of future sales, and it should cover the city's costs.
"I certainly think it would be appropriate for AEG to offer to reimburse the city for some of our costs. I think that's something you're going to hear the city council probably ask for," said Hahn.
But Mayor Antonio Villaraigosa says it's the city's responsibility and taxpayers are footing the bill.
"We're obligated to provide those services and this is just a lot of noise frankly about nothing," said Villaraigosa.
The LAPD deployed 3,200 officers and other personnel after projecting that as many as 250,000 people would gather on the streets surrounding Staples Center. Beyond ticket holders, only about 1,000 fans showed up.
The Associated Press contributed to this report.