But the interview offered a glimpse into the psyche of an enigmatic man who was catapulted from obscurity onto the national stage a month ago when he won the primary for the Democratic nomination for the Senate. He will face Senator Jim DeMint, a Republican, and Tom Clements of the Green Party in November.

Image A local newspaper took interest. Credit... Travis Dove for The New York Times

The central mystery of how he captured more than 100,000 votes, or 59 percent, against a candidate who, unlike Mr. Greene, actually campaigned remains unsolved.

Top Democrats say Mr. Greene was put up to the race by mischief-making Republicans; others say he might have won simply because his name appeared first on the ballot. Mr. Greene says he won by “hard work” but cannot name anything he did.

No evidence of fraud has surfaced. And on Friday, the State Law Enforcement Division, which was investigating Mr. Greene’s finances, cleared him of any wrongdoing.

It was trying to square how he could have afforded the $10,440 filing fee in March to get on the June 8 ballot when just a few months earlier he was apparently poor enough to be assigned a public defender to represent him on a felony obscenity charge.

“After a thorough investigation, SLED has concluded that there is no evidence of wrongdoing, criminal intent or deception to the court when Greene applied for a public defender last year,” the agency said. It also determined that he paid for the filing fee with his own savings from the Army, as he has said all along. (The base pay for an E-4 in 2009 with at least six years of service was $2,219 per month.)

He is still due in state court Monday on the obscenity charge, in which a student at the University of South Carolina said he showed her pornography and tried to go to her dorm room with her. Afterward, a relative paid the $500 fee to a bonding company for him to be released on $5,000 bail.