Nolan Wells Death Records Inadvertently Released by Mississippi Agency

The Mississippi Department of Marine Resources says it mistakenly released records tied to Nolan Wells' death investigation ... and now prosecutors are telling the agency to keep the rest under wraps.

In a letter responding to a TMZ public records request, the MDMR acknowledged it had "inadvertently released records" related to Nolan's case. The agency did not identify which records were disclosed or to whom they were released.

The MDMR says it was later notified by Jackson County District Attorney Angel Myers McIlrath that Nolan's death remains under investigation and will be presented to a grand jury.

McIlrath said the agency's involvement in the search for Nolan -- along with assistance it provided to the Jackson County Sheriff's Office -- is part of that investigation and therefore exempt from public disclosure.

The D.A. asked the MDMR to refrain from releasing any more protected information ... and the agency says it is withholding the records TMZ requested.

As you know ... Nolan disappeared from Horn Island during a Fourth of July boating trip with friends, and his body was found in the water two days later.

Authorities have said they believe he drowned and have not found evidence of a crime ... though an official cause and manner of death have not been released.

We obtained a video from the gathering ... and it appears to show Nolan in swim trunks on the back of a boat. It's believed to be the last image of him alive.

An independent autopsy commissioned by Nolan's family found a large area of red discoloration on the back of his head that could indicate a possible injury ... but the cause and manner of death are undetermined pending investigation.