Duane Davis is widely believed to have spoken to federal authorities in Los Angeles about Shakur ‘s murder in a deal in which his statements couldn’t be used against him.

Could a deal struck 14 years ago between California officials and the suspect in the murder of Tupac Shakur jeopardize the Nevada prosecution in the death of the hip-hop icon? Experts say it could get messy.

It’s widely believed that Duane Keith Davis, also known as “Keefy D” or “Keffe D,” talked himself into his arrest on a murder charge in connection with the killing of Shakur in Las Vegas in 1996.

Davis had reached a deal with federal investigators in Los Angeles to speak openly about a number of topics in 2009, including his knowledge of Shakur’s killing.

While the exact terms of the agreement are unclear, prosecutors presumably wouldn’t be able to use those statements against him. But that doesn’t mean Davis’ statements couldn’t be used as an investigative tool — and that his own chattiness in the years since he got a semi-free pass couldn’t come back to hurt him.

The lack of clarity could lead to a courtroom fight, experts said.

Can the California agreement apply to the Nevada prosecution?

“If there’s an agreement, there’s some expectation that another jurisdiction would give full faith and credit to what this jurisdiction has done,” said Veronica Galván, a judge in Washington state who has taught at the National Judicial College in Reno, Nevada.

“But I would also presume that that’s done with the knowledge of that other jurisdiction, that it was communicated with that other jurisdiction, ‘Hey, we’re getting these statements, this is what we intend to do, are you cool with that?’ And the feds normally do not make a proffer without bringing in the state” where another crime might have been committed, Galván said.

Whether Davis’ previous statements tied to his disclosure to the feds are admissible in a Las Vegas courtroom might not be cut and dried.

Las Vegas criminal defense lawyer Tom Pitaro said he’s confident the Clark County district attorney’s office has been careful not to use any protected words from Davis.

“There are experienced prosecutors in this case; they’re not rookies,” Pitaro said. “And given the nature of this case and the publicity — I mean, this happened nearly 30 years, and here we are still talking about it — I would think they would not make a mistake like that.”

The killings of Tupac and The Notorious B.I.G.

Davis was invited to speak to investigators about his knowledge of the Shakur and Biggie Smalls killings.

Smalls, better known as The Notorious B.I.G., was gunned down on March 9, 1997, in Los Angeles, prompting authorities in Southern California to offer Davis some leeway to chat about it.

“There was a history of violence, and it just culminated in both the murders of Tupac and Biggie,” said retired Los Angeles police robbery-homicide Detective Greg Kading, who interviewed Davis.

Even though the deal prohibited Davis’ words from being self-incriminating, Kading insisted that any statements could be used as an investigative tool — and that any subsequent comments from him are also fair game.

“The proffer agreement simply said that when you sit down and talk to us, whatever you say that is self-incriminating, we won’t use against you. It’s not immunity,” Kading said.

“But when he leaves that room, that agreement doesn’t apply to everything else in his life, as he erroneously believed, so he began to go out and boast about his involvement in the murder. None of that’s protected under the agreement.”

‘We wanted to make sure we get it right’

Clark County District Attorney Steve Wolfson said he’s confident in the admissibility of the state’s evidence.

“This is an important case. We wanted to make sure we get it right,” Wolfson told reporters Wednesday in Las Vegas shortly after Davis’ first court appearance. “We wanted to make sure we had legally admissible evidence. We wanted to make sure we felt comfortable that we had sufficient legal evidence.”

A grand jury in Clark County handed up a murder indictment last week accusing Davis, 60, of having orchestrated the fatal drive-by shooting of Shakur in Las Vegas on Sept. 7, 1996.

The case was “reinvigorated” in 2018 by “Davis’s own admissions to his involvement in this homicide investigation that he provided to numerous different media outlets,” Las Vegas Police Lt. Jason Johansson told reporters last week.

Davis has admitted in his 2019 memoir, “Compton Street Legend,” to having been in the car that carried Shakur’s attackers that night. Notes and other written materials tied to the book were seized in August as part of a search of Davis’ home in Henderson, Nevada.

Criminal defendants have a penchant for speaking more freely in later life, even if it could be against their legal self-interest, Pitaro said.

“It happens with a lot of people,” he said. Referring to the late mob boss and author, he said, “Look at Joe Bonanno … thinking, ‘I can just write a book and profit off all my crimes.'”

Davis has also said he has been diagnosed with cancer, believed to be another factor in his willingness to speak up about the 1996 slaying in Las Vegas.

“I don’t know his current medical condition,” Wolfson said Wednesday. “I’m not going to speak to whether he’s still suffering from cancer or not.”

Similarities to the Cosby case

Davis’ case could have some parallels with that of disgraced comedian Bill Cosby, who was convicted in 2018 of drugging and assaulting former Temple University’s women’s basketball administrator Andrea Constand in 2004.

However, the Pennsylvania Supreme Court tossed out the conviction in 2021 because Cosby gave incriminating statements in a civil lawsuit.

Cosby believed he was able to speak openly because previous Montgomery County District Attorney Bruce Castor said he wouldn’t prosecute Cosby if he agreed to give a deposition in the civil matter.

Years later, new Montgomery County DA Kevin Steele pursued a successful prosecution of Cosby, believing there was no explicit deal between Cosby and his office. The state’s high court disagreed.

But unlike any possible issues with Davis’ words to the feds in California and prosecutors in Nevada, the Cosby case was a straight line within the Pennsylvania office.

“It’s the same entity. You are bound by the promises that were made by your predecessor, because the agreement was not made with you;; it was made with the office,” Galván said.

The prosecution of Davis has a series of other challenges — most notably, the Clark County DA’s admission that he’s believed to be the last person alive who was in the car from which Shakur’s attackers opened fire.

The man believed to have pulled the trigger — Orlando Anderson, Davis’ nephew — was killed in a 1998 gang shooting in Los Angeles.

Davis appeared in court Wednesday, and a judge granted his request for a two-week delay so newly hired defense lawyer Edi Faal, who is based in California, can go to Las Vegas.

But it wasn’t entirely clear whether Faal will be Davis’ lawyer for much longer.

“I am tasked with helping him retain counsel in this case,” Faal told NBC News in a statement. “I will not comment on the case.”