By Holly Yan, CNN
(CNN) — As Nolan Wells’ family prepares to lay the 18-year-old to rest on Monday, they will do so without knowing why his young life was cut so tragically short.
It’s been 16 days since Wells and his friends went on a Fourth of July boat trip to Horn Island — a popular destination for holiday revelers off the Mississippi coast with no shelters, no facilities and no communications.
His friends made it back home. Wells, a student and wide receiver at Southwest Mississippi Community College, did not. His body was found two days later, on July 6, facedown in the water off the shoreline of Horn Island by a National Park Service agent.
While his loved ones mourn, some of Wells’ friends who were on the trip have received death threats. Photos from the excursion show Wells hanging out with what seem to be all-White friends, leading some to evoke harsh feelings about Mississippi’s fraught racial history and speculate about whether race played a role in his death.
Others say the currents near Horn Island can be notoriously rough, with the local coroner saying his office has received numerous drowning victims from Mississippi’s barrier islands in recent years.
Here’s what we know and don’t know about the case that has spurred national attention:
What was the cause of death?
Two concurrent autopsy investigations are underway to determine Wells’ cause and manner of death.
The Mississippi State Medical Examiner’s Office is conducting the official autopsy investigation, Jackson County Coroner Bruce Lynd said.
There were no immediate, obvious signs of foul play or trauma on Wells’ body, Lynd told CNN. But due to the uncertain circumstances, “we asked for an autopsy (at) the state medical examiner’s office so that they could do the full autopsy and be able to tell if there was any foul play or trauma,” he said.
The state medical examiner’s office performed an autopsy on July 7 and has been waiting for results from toxicology tests, Lynd said. It can take weeks to receive results from toxicology tests, which are standard in death investigations.
Separately, Wells’ parents sent their son’s body out of state for an independent autopsy, family attorney Ben Crump said.
“We had his body flown from Mississippi to Washington, DC, because his family wanted to make sure that they had a doctor who had no ties to Mississippi law enforcement to do an independent examination of their son’s body,” Crump said.
Results from the independent autopsy are still pending, Crump said.
What was Wells doing when a friend last saw him?
Tracestin Shepherd, who was on the trip, described Wells as one of his best friends. He told ABC’s “Good Morning America” he took a boat back from Horn Island in the late afternoon of July 4, but Wells stayed behind with a girl he had met.
“They met that day, and it was kind of – it’s kind of one of those things. … he really did like her, but that was the only time they ever hung out was at Horn Island on July 4,” Shepherd told GMA.
Shepherd said he has spoken to investigators and Wells’ friends from the trip have been cooperating with authorities.
But Jayvon Williams, another friend who also saw Wells on July 4, said it’s not like Wells to separate from the group he came with.
“I don’t think that Nolan would say, ‘Bro, I’m staying with this girl on the island. Y’all go ahead and go back,’” Williams told CNN’s Laura Coates.
“I’ve never known Nolan to stay back, watch friends leave. He’s always been a guy where, if he rode with you, he’s gonna come back with you,” Williams said.
Williams was supposed to be on the same boat as We