Nolan Wells' Friends Send Legal Letter Threatening to Sue Reverend Al Sharpton

1:43 PM -- Al Sharpton tells TMZ ... "I welcome the lawsuit and will have my attorneys be in touch with theirs to arrange for them to serve me so we can get in court."

Sharpton says ... "I convened a prayer vigil on what would have been Nolan's 19th birthday and three of the young men joined the Zoom and I asked them to come forward. While I did not know their names, so I did not defame them, we have a right and a duty to raise questions that were raised to me by Nolan's parents."

He continues ... "From the onset of this case, I publicly stated that I welcomed any litigation that would legally require every person that was with Nolan Wells before his death to be forced to answer questions under oath. Litigation requires depositions, discovery and a complete examination of the facts."

Sharpton concludes ... "I have been involved in the case for one sole reason: To help Nolan's parents Christine and Elmore find the truth in what happened to their beloved son through a transparent and accountable investigation. If a lawsuit is a catalyst for the truth, then it is welcomed and it will not deter NAN or me from continuing to stand with the family in their pursuit of justice."

Nolan Wells' friends are tired of Reverend Al Sharpton insinuating they had something to do with his death ... and they've sent a legal letter demanding he stop.

The legal team representing Warren Hudson, Jax Pitalo and Morgan Seymour sent the letter to the reverend Friday ... claiming they're ready to file a civil lawsuit against him for making repeated false statements suggesting that they had something to do with Nolan's death.

The lawyers highlight a series of statements made by Sharpton -- including during an interview with TMZ last month -- which they say imply the three friends aren't being forthcoming -- and may even have something to do with Nolan's death.

Hudson, Pitalo and Seymour are also calling out Rev. Sharpton for using a vigil set up in Nolan's honor to go after the three of them.

Ultimately, the three young men call on Rev. Sharpton to repent for his comments ... demanding that he publicly apologize and retract his statements. Even if he does, they're reserving all rights to sue him.

As you know ... shortly after Nolan's body was found off the coast of Horn Island near Mississippi, many prominent voices began to question whether he'd accidentally drowned or if there was a more nefarious explanation for his death.

So far, there has been no official cause or manner of death.