He has accused Dutschke of stalking him online, a claim the former taekwondo instructor has denied.
Dutschke told reporters this week that he did not know Curtis well.
"He's just a little nutty. I don't have a relationship with him," he said.
"I've met him two times in person, and then there was a third time we sent e-mails back and forth."
In the e-mail exchange, according to Dutschke, he accused Curtis of posting a fake membership certificate for MENSA, the high-IQ organization. Curtis acknowledged that he posted a fake certificate, but said he did it to catch Dutschke stalking him online.
Ties to letters?
Authorities have not said how they linked the letters to Dutschke, who appears to have personal ties to at least two of the three people who were sent letters.
In 2007, Dutschke failed in his bid as a Republican to defeat Democratic state representative Steve Holland, whose mother, a judge, received one of the ricin-tainted letters.
"We just want to move on," Holland told CNN, adding that he wanted justice for his mother.
"This could have been devastating. Mom could have died had this taken the worst-case scenario."
Dutschke also has said he has met Wicker.
Dutschke, meanwhile, faces molestation charges in an unrelated case.
According to a grand jury indictment handed down this month and obtained by CNN, he is accused of molesting three girls under the age of 16. The accusations go back as far as 2007, according to the indictment.
Dutschke has repeatedly denied the charges in interviews with local media, and he pleaded innocent in court this month.
He closed his taekwondo studio after the allegations were made public.