Nolan Wells died during a Fourth of July trip to Mississippi’s Horn Island, and investigators are still working to determine what happened.

The 18-year-old football player was reported missing hours after he traveled with a group of friends to the barrier island off the Mississippi Gulf Coast. His body was found on the northwest end of the island two days later. Subsequently, the local Jackson County Sheriff’s Department coordinated an autopsy with the state medical examiner.

Though the autopsy results are pending and authorities believe Nolan may have drowned, his parents launched their own investigation, arguing that the information presented to them — including why he would have separated from his friends — doesn’t add up.

Christine Wonsley told Good Morning America on July 20 that she couldn’t “fathom” her son going off alone.

“We always taught him that if you go with a group, you stay with a group,” his father, Elmore Wonsley, added. “If you go with five, you come back with five. Do not separate from the group. Because I always said, ‘Safety is in numbers.’ So he knew to stay with this group, so why would he split from the group? I don’t know.”

Here’s everything to know about what happened to Nolan Wells and what the investigation has revealed about his death, so far.

Wells went missing after taking a boat trip with friends

On July 4, Nolan left to take a boat ride with friends to Horn Island, a trip that Elmore told GMA was meant to be his “last hurrah” before he returned to football camp at Southwest Mississippi Community College.

One of his friends reported him missing to the U.S. Coast Guard around 11 p.m., and his mother filed a missing persons report with the Jackson County Sheriff’s Department after midnight.

His friends left the island without him

Jackson County Sheriff John Ledbetter told the Associated Press that Nolan’s friends, who have cooperated with the investigation, claimed that the teen opted to stay on Horn Island when his group left.

“From the people we’ve talked to, it sounds like he chose to stay on the island with the assumption that he was going to ride back to the mainland with someone else,” he said.

Chancery Court Judge Ashlee Cole, whose son was one of the friends Nolan traveled to Horn Island with, said the same in a lengthy Facebook statement.

She wrote that her son left because the boat he was on began taking on water and that “Nolan made a decision to stay on the island and return inland later with another group of friends.”

However, while speaking with ABC News, Christine and Elmore’s attorney, Ben Crump, claimed there are conflicting accounts involving Wells’ plans and whether he intended to rejoin his friends after speaking with a young woman or not.  

“The boys on the boat said, ‘No, Nolan told them he was going to stay with her,’ ” the lawyer said. “She’s saying he went and got on the boat. They’re saying he didn’t get on the boat. So which is it?”

Wells’ body was found two days later

On July 6, a body was discovered in the water on the northwest end of Horn Island.

Jackson County Coroner Bruce Lynd later told PEOPLE that they positively identified the remains as Nolan’s through dental records, but did not speculate or reveal a potential cause of death.

In an interview with ABC News, Ledbetter said that investigators did not expect foul play and that there was no evidence leading them “to believe that a crime has occurred.”

United Cajun Navy vice president and spokesperson Brian Trascher told PEOPLE that though there were photos of “the boys drinking beer and stuff,” he believed “Nolan’s blood alcohol level was not at an intoxicated level.”

Police have asked for photos and videos “depicting alleged altercations” on the island

Nolan’s disappearance sparked an intense online debate after a video went viral that claimed to have audio of the teen in a verbal argument. Ledbetter told the Sun Herald that they’re still in the process of authenticating everything that’s been presented.

“A lot of people are calling here to report what they saw or read on social media, and it’s not firsthand knowledge,” he said. “What we have to go on in an investigation is original documentation and firsthand knowledge.”

Ledbetter continued, “One barrier we have is social media. We are in the process of documenting, verifying, and corroborating all that information.”

To help authorities distinguish information pulled from the internet from “true firsthand knowledge,” the Jackson County Sheriff’s Department issued a call for original, unedited photos and videos from anyone who was on or near Horn Island on July 4.

WDSU reported that police are specifically looking for original media “depicting alleged altercations or containing images of, or believed to include Nolan Wells” as well as information from anyone who may have “observed or heard an argument, disturbance, or other unusual activity while on the island that day.”

His family launched an independent investigation

Nolan’s family has since launched an investigation into his death, independent of the Jackson County Sheriff’s Department. On July 10, Crump told GMA that they were in the process of doing an independent autopsy in Washington, D.C., with help from former NFL quarterback Colin Kaepernick.

Crump said they’re also seeking forensic analysis of the teen’s phone, which was recovered by Christine’s friend after it was tracked using Life360. Nolan’s mother claimed that the device’s location history differed from what his friends saw on Snapchat and that there were no posts from his two Snapchat accounts on that day, which she said was unlike her son.

“It isn’t even 24 hours, which is how long videos and pictures stay in Snapchat,” Christine told GMA. “I’ve seen Nolan whenever he snaps. When he goes and he’s having fun, he does videos. There was absolutely nothing.”

In a separate interview with ABC News that aired on GMA, Ledbetter confirmed that they have requested Nolan’s phone for investigation, but haven’t yet received it.

“We’re working toward the same goal as the family,” he said. “We want a thorough investigation. That’s what we’re going to continue to do until we arrive at the answers that the family deserves.”