The Los Angeles Police Department used an invalid court order and spent $22,000 to bring an imprisoned killer and former gang leader to speak to an exclusive dinner for private executives, according to a report released Friday.

In all, 38 LAPD employees worked about 320 hours to prepare for the January event at a downtown building and protect Rene "Boxer" Enriquez while he was there, the inspector general of the city's police commission wrote.

What's more, the department didn't have authority in the first place to remove Enriquez from custody because it used an order from a 2012 murder case that has been closed — and in any case only allowed his release to act as a witness — the departmental watchdog's report said.

Enriquez, an ex-Mexican Mafia leader has been in prison since 1993 on a 20-years-to-life sentence, has gained allies in law enforcement. Gov. Jerry Brown has acknowledged Enriquez's past cooperation with authorities but denied him parole last month, saying his history of violence meant he still presented "an unreasonable danger to society if released."

The decision came despite letters of support from the FBI and several federal prosecutors.

In recent years, Enriquez had talked to various groups of officers and provided valuable information on the transnational criminal enterprise to which he once belonged, Los Angeles Police Deputy Chief Michael Downing said in the days after the event.

On Friday, the department issued a short statement, saying that Chief Charlie Beck had asked his professional standards bureau to launch its own investigation. Beck already had said the department's role in the event was a mistake.

The watchdog agency revealed new details about the event that almost immediately attracted criticism from the mayor and police commission president.

According to the report:

In December, a commanding officer at LAPD characterized the event as a law enforcement training session in asking Beck to approve the use of department resources, which he did. Those resources would eventually include officers making three visits to Enriquez before he spoke, a police helicopter to scout his route to the building, and SWAT officers who secured the area.

The event attracted 175 people invited by a chapter of the Young Presidents' Organization, which describes itself as "the world's premier peer network of chief executives and business leaders." Four LAPD officers attended, as did 10 other "high-ranking law enforcement executives" from other agencies.

The invitation promised a once in a lifetime chance to hear a mystery guest, promising that attendees would be "amazed, shocked, blown away and maybe even a little scared."

Inside the room, the presentation included some theatrics.

"Silhouetted behind a screen, Enriquez described how an organization creates, delivers, and accumulates value economically, socially, and culturally," the report said. "It was not until the curtain was lifted that the audience saw Enriquez standing on a small stage, in a black business suit, with his hands cuffed to waist chains and his legs in shackles."

Once the handcuffs were removed, he explained who he was and how the Mexican Mafia worked.

Afterward, guests went for a buffet dinner. They were allowed, in pairs, to meet Enriquez — who signed copies of a 2009 book about his life.

On Friday, Los Angeles Police Commission President Steve Soboroff credited the police chief for taking "the action necessary to do a thorough personnel investigation." The commission is an independent civilian board that oversees the department.