The Humphreys County Medical Examiner found that Greer drowned in the waters of Kentucky Lake in Humphreys County, Tennessee, The Tennessean reports. He tested positive for marijuana and a low level of alcohol, the paper claims, citing a toxicology report. A fleet of first responders searched for the teen after he fell from a boat while on a tubing trip with his friends on July 10.
Greer’s body was recovered from the water a day later, with Humphreys County Sheriff Chris Davis saying at the time, “It was just as simple as hitting a wave and turning over and not coming back up.”
Humphreys County Assistant Medical Examiner Erin Carney told The Tennessean that Greer was riding on an inner tube behind a boat when the tube flipped, sending Greer under the water.
More than a week after Greer was found, Morgan, 51, released a moving statement about the teen’s death.
“The loss of our son Jerry is the hardest thing we have ever had to endure as a family. Karen and I are so grateful for all of the wonderful people who have shown us unwavering support during this difficult time,” the country singer wrote in a Facebook post.
The hours following Greer’s disappearance were filled with mystery, with a rep for the Tennessee Wildlife Resources Agency telling PEOPLE, “We are not sure yet why he did not resurface.”
It remains unknown why the teen went under despite wearing a life jacket.
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RELATED VIDEO: WATCH: Jerry Greer, Son of Country Singer Craig Morgan, Found Dead After Tubing Accident
In a previous statement to PEOPLE, Morgan’s rep said that Greer had plans to play football for Marshall University in the fall.
“The family is grateful for the outpouring of support and requests prayers at this time as they privately mourn this terrible loss,” the rep added. “Jerry is survived by parents Craig and Karen Greer, sister Aly Beaird and brother-in-law Ryan Beaird, brother Kyle Greer and fiancée Chelsea Rogers and brother Wyatt Greer.”
Morgan, an Army vet and avid hunter, has several Top 10 country hits and is the host of Craig Morgan: All Access Outdoors on the Outdoor Channel.