Shain Gandee Died of Carbon Monoxide Poisoning
updated 04/02/2013 AT 01:45 PM EDT
•originally published 04/02/2013 AT 03:45 PM EDT
The 21-year-old reality TV personality, his uncle and another man who has not officially been identified were found unresponsive in Gandee's Bronco on Monday morning, after being reported missing since early Saturday morning.
"Foul play has been ruled out," Kanawha County Commissioner Kent Carper of West Virginia told PEOPLE on Tuesday.
Autopsies later confirmed the men died of the gas and that the deaths were accidental.
With the vehicle knee-deep in mud, toxic fumes from the car were likely unable to escape through the tailpipe, authorities say.
Gandee's cousin, Ashley Gandee Lewis, says on Facebook: "The family feels that Shain died peacefully in his sleep without pain or suffering."
The family, meanwile, is making funeral arrangements. "Nothing is confirmed but they are thinking Saturday," says the post. "So private or public hasn't been decided. I will try to keep everyone updated :(."
Gandee – whose MTV bio page described him as a "sociable and loyal" family man – is remembered by the network as "a magnetic personality, with a passion for life that touched everyone he met and we will miss him dearly."