Sheriff Marlin Gusman has asked outside law enforcement agencies to investigate the death of Willie Lee, an Orleans Parish Prison inmate who died in March after a fight with another inmate.

The sheriff’s request came after Coroner Jeffrey Rouse determined that Lee died of “cardiac arrest as a result of an inmate-on-inmate physical altercation.”

Rouse last week ruled Lee’s death a homicide , a classification that prompted Gusman to request an independent inquiry, even as the Sheriff’s Office wraps up its own investigation into the death.

Gusman, in a prepared statement Monday, said it is “vital that the Sheriff’s Office maintains transparency in the investigation.”

“I insist upon maintaining public confidence in the integrity of the entire investigations process,” the sheriff wrote in a letter to Col. Mike Edmonson, the State Police superintendent. “I assure you that all members of my staff will fully cooperate with your investigators and will provide any documentation or assistance needed.”

While Gusman reached out to the State Police late last week, the New Orleans Police Department actually will lead the murder investigation, said Tyler Gamble, an NOPD spokesman. The sheriff spoke with Superintendent Michael Harrison on Monday and agreed the NOPD will take the lead, Gamble said.

“State Police could still play a supporting role in the investigation,” Gamble said. “We’re immediately working it as a murder investigation. We’re the agency that investigates murders in the city of New Orleans.”

The state Attorney General’s Office and FBI also were consulted about Lee’s death and the coroner’s findings, but it remained unclear Monday what role they might play, if any.

“Our investigators will be meeting with (Orleans Parish Sheriff’s Office) investigators in the coming days,” said Sgt. Nick Manale, a State Police spokesman. “Obviously, every incident is unique, and we just want to make sure” the appropriate agencies are involved.

Lee, 40, died March 23 shortly after a fight with a fellow inmate at OPP. At the time, authorities said Lee had died from extensive heart disease. Last week, Rouse acknowledged Lee suffered from advanced coronary artery disease but blamed his death on the physical exertion of the fight.

No criminal charges have been filed in the case, even though Sheriff’s Office investigators reportedly have identified the other inmate involved in the fight.

It wasn’t clear why the sheriff waited eight months to ask another agency to investigate Lee’s death, and a Sheriff’s Office spokesman did not respond to a question about the timing of the request for an independent review. However, the move drew praise from inmate advocates who have been critical of Gusman and his stewardship of OPP, a troubled lockup that remains the subject of court-ordered jail reforms.

“It’s a very positive move, and we’re glad that the sheriff is doing so,” said Katie Schwartzmann, the MacArthur Justice Center attorney whose class-action lawsuit on behalf of inmates resulted in a federal consent decree Gusman signed with the U.S. Department of Justice. “Outside, independent review will increase public confidence in the integrity and transparency of investigations into deaths in the sheriff’s custody.”

Lee’s death led to renewed criticism and even protests over the allegedly lax supervision at OPP, where violence remains commonplace. Lee’s death was the 25th at the prison since 2009, according to the group Orleans Parish Prison Reform.

The Times-Picayune obtained surveillance footage of the fight involving Lee, which occurred in a temporary housing tent, and reported last week that inmate Jeremy Cleckley, 31, can be seen in the video throwing several punches at Lee, sending him “sprawling over a table.”

“Cleckley stands over Lee, who is lying face-down on the tabletop, clasps his hands together, raises them in the air and brings them down on or near Lee’s head,” the newspaper reported.

According to the Sheriff’s Office, Lee began complaining about having difficulty breathing and collapsed 13 minutes after the fight. He died about two hours later.

“His heart was a ticking time bomb,” Rouse said of Lee in an interview last week, “but eventually, it was the actions of the other person that caused it to go off.”

Rouse noted that he does not believe any deputies inflicted Lee’s fatal injuries. He said his findings had been based in part on surveillance video of the fight, adding that none of the bruising and other injuries Lee suffered caused his death.

The classification of Lee’s death as a homicide came shortly after Rouse announced a series of new policies on how his office will respond to in-custody deaths — cases that historically have been steeped in controversy in New Orleans. Rouse’s predecessor, longtime coroner Frank Minyard, often was faulted because his forensic examinations tended to clear law enforcement of wrongdoing in such cases.

Follow Jim Mustian on Twitter, @JimMustian.