An ex-Mexican Mafia leader serving life in prison for murder was escorted by Los Angeles officers to speak at a gathering of police chiefs and business leaders, prompting criticism from the mayor's office and an acknowledgement of mistakes from the chief of police Thursday.

Rene "Boxer" Enriquez gave a PowerPoint presentation Wednesday and spoke about how he was instrumental in building a transnational criminal enterprise that held influence over tens of thousands of violent gang members. Attendees were provided refreshments and a book about Enriquez's life and rise to power.

"Mistakes were made in holding this event," LAPD Chief Charlie Beck said in a statement late Thursday. "I have directed the Department to more thoroughly review future events before committing LAPD resources."

The event's speaker had previously talked to law enforcement officers, including personnel from federal agencies, 15 times or so over the years, Los Angeles Police Deputy Chief Michael Downing said.

Mayor Eric Garcetti's spokesman Yusef Robb released a short statement that read: "This was inappropriate and should have never happened. We expect a full accounting of why this occurred, and we are going to make sure this sort of thing never happens again."

The criticism came a day after Steve Soboroff, head of the department's civilian oversight commission, requested that the LAPD's independent inspector general review the incident. He said the public was unnecessarily endangered.

"If you step back and look, the perception is it's like `meet a real-life Mexican Mafia informant and have some hors d'oeuvres and get a book,"' Soboroff said. "That's not the purpose of training."

"Those were the true judgment errors," he added.

Enriquez spoke at a downtown Los Angeles building that required 23 elite LAPD officers to secure. The roughly 90-minute meeting, first suggested by a chapter of the Young Presidents' Organization, provided valuable information on the growth and operations of a transnational criminal enterprise, said Downing, who heads the department's counter-terrorism and special operations bureau.

Soboroff said the training may have been valuable, but the location was problematic and civilians shouldn't have been allowed to attend. He said SWAT officers had to be in place six hours in advance to secure the area. He said the event could have instead been held in an already secure location such as a police station.

Linda Fisk, a spokeswoman for the Young Presidents' Organization, didn't respond to requests for comment.

Police chiefs from at least eight departments around the region attended the event along with detectives from LAPD's Robbery-Homicide Division and others, Downing said.

Downing said other people might be brought out of prison for law enforcement purposes. He declined to comment on whether he would restage an event such as the one Wednesday with Enriquez.

"I don't think we should be so risk adverse that we're afraid," he said. "I think it helps us work smarter, I think it helps us look over the horizon to see what threats are coming (and) what we can do to build better strategies."