Authorities are uncovering more clues about how MTV reality star Shain Gandee and two other men died over the weekend. The 21-year-old star of MTV's "Buckwild" was found in his 1984 Ford Bronco in a remote area of Sissonville, West Virginia.

Police say they believe Gandee left a

local bar at around 3am ET Sunday morning with his uncle, David Gandee, and another man and they told people they were going off-roading. The men were missing for over a day before an ATV rider spotted the SUV partially submerged in mud.

Trace Gallagher reported that authorities are looking at carbon monoxide poisoning as the possible cause of death because the muffler was beneath the mud.

MTV has placed the second season of "Buckwild" on hold.

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