An avid user of both CB radio and the Internet, Marquis apparently had angered some people by selling CB equipment over the Internet, but not delivering.
A series of Internet messages complain about Marquis, even threaten to harm him, and warn others about dealing with him.
A bomb delivered from out-of-state killed Marquis Thursday as he was opening the package, which just had been delivered by United Parcel Service.
The blast seriously injured his mother, 52-year-old Sheila Rockwell, who was also in the room.
Police say the package bombing is the first of its kind in the state, and it will be treated as a homicide.
Pat Richards, who heard the blast, told CBS affiliate WCAX: "I was walking with a friend, and we heard a loud 'boom' that made your heart stop for a second. My first impression was that it was a furnace that blew up."
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