2:42 PM PT -- Law enforcement sources tell TMZ ... Bloomington Police accessed the thumb drives and determined there was no confession by O.J. Simpson.

We're told ... not only was there no confession, there was no O.J. on any of them -- it was just Iroc Avelli talking to himself.

New twist in the murders of Nicole Brown Simpson and Ron Goldman ... police claim they have reason to believe they have a recording of O.J. Simpson confessing to the murders.

According to a new search warrant, obtained by TMZ, cops in Minnesota say they have a thumb drive they were told has a recording of O.J. admitting to the double murder of Nicole and Ron.

What's more, police say they've been told the recording also features O.J. implicating an unknown third party.

In the warrant, cops say they seized a backpack containing multiple thumb drives from a man named Iroc Avelli as part of an investigation in a separate case. Avelli is Simpson's former bodyguard.

The docs say Avelli was arrested in March 2022 and police executed a search warrant to collect evidence, including a green backpack with live ammunition and other items.

Bloomington PD in Minnesota says in June 2024 -- 2 months after O.J. died -- they got a call from an LAPD detective who advised that Avelli and his attorney met with LAPD and told cops inside the green backpack was a thumb drive with the recording of O.J.'s confession.

In order to access the contents of the thumb drive, Minnesota cops needed a new search warrant ... so they went to a judge in June and got permission.

But, here's the thing ... legal docs say the results of what's actually on the thumb drive are still pending.

Our law enforcement sources say the thumb drive in question was tied up in ongoing litigation ... with Avelli and his lawyer suing the Minnesota cops to get back all his seized items -- however, in July, a judge denied a motion to return the belongings.

So, as it stands, the drive is in Bloomington PD's custody, but we don't know if they've dug into what's on it ... or whether they've shared any info with LAPD.

As you know, O.J. was charged in 1994 with Nicole and Ron's murders. He was acquitted in the "Trial of the Century" ... though he was later found liable for their murders in a civil case.

Simpson's longtime attorney and executor of his will and trust, Malcolm LaVergne, tells TMZ ... he thought LAPD considered the murder case closed, that their position was O.J. did it but beat the case, and that police have never actively looked for any other suspects since the end of the criminal trial in 1995.

LaVergne says he's trying to get his hands on all the evidence -- including the suicide letter, gloves and the pullover cap -- to auction off to cover Simpson's debts ... but this thumb drive could be the most crucial evidence yet.