This article contains details about an autopsy result that may be distressing

The cause and way in which Mississippi teenager Nolan Wells died after going missing earlier this month are still unknown following a preliminary independent autopsy.

The body of Wells, 18, was found in the water near Horn Island two days after he did not return with friends from a boating trip there on 4 July.

The Jackson County Sheriff's Office said they did not suspect foul play, but Wells' family requested an independent autopsy to address what they say are "serious, unanswered questions about the circumstances that left Nolan alone on the island and about how he died".

Initial findings from the autopsy show foul play cannot not be ruled out, the family's lawyer said on Wednesday.

Ben Crump told a press conference that the exam had found some red discoloration on the back of the teenager's head, the cause of which has not been determined.

The examiner, forensic pathologist Dr Roger Mitchell, did note there were no wounds on the skin or fractures of the skull in the area.

Mitchell, according to Crump, could not determine if there was any bruising on Wells' body because it had been too decomposed, nor could he tell if Wells was conscious or unconscious when he went into the water.

If Wells did drown, determining how he got into the water and whether or not he was conscious or unconscious when he did so is the "crux of the matter," Crump said.

Mitchell's autopsy report also stated that parts of Wells' throat had been held back following the initial autopsy, which is standard practice if there are any concerns.

"Therefore, this pathologist cannot rule out injury to the neck as a contributing a contributor or a cause of death," said Crump.

Mitchell also noted that the original toxicology results had not yet been received.

"We have more questions than answers at this time," said the lawyer, who specialises in wrongful death lawsuits.

The results from an initial autopsy carried out by the Jackson County Coroner have not yet been released. The BBC has contacted them for comment.

Crump and the Wells family have questioned conflicting reports that have surfaced in the time since Wells went missing.

His mother Christine Wonsley was the first to raise the alarm that her son, who played American football at Southwest Mississippi Community College and was described by his coach as a "happy-go-lucky kid", had gone missing after he did not return on the evening of 4 July.

She said she was bothered that her son's mobile phone and car keys had been found with his friends after they returned from Horn Island and felt "uncomfortable" about the police saying her son had accidentally drowned.

Crump has also questioned this, saying: "This is a kid who knew how to swim."

"It is our hope that our local authorities will do what they need to do, because us having the preliminary autopsy results and hearing nothing from them — it's heartbreaking, and it's concerning," Wonsley said on Wednesday. "Which again is why we are here, why we have asked for this help."