A Ramsey County judge has convicted a St. Paul man of having cybersex with a child -- a felony under state law -- though the defendant claimed the boy had lied online by claiming he was 16, the age of consent for such activity.

Thomas F. LaBlanc was found guilty of solicitation of a child for sexual conduct via the Internet, punishable by up to three years in prison or a fine of up to $5,000, or both.

He was prosecuted under a state law that makes it a crime to solicit children to engage in sexual conduct or to communicate sexually explicit materials to them. The defense challenged the law's constitutionality.

The communications began in early 2009 after the Missouri boy wrote to LaBlanc via social media, asking to be his "friend." The boy's Myspace profile said he was 16 but he was 15.

LaBlanc, 66, a Native American dancer who traveled around the country, goes by the names "Tatonka" and "Strong Buffalo." The teen said he first saw LaBlanc dance at his school in Missouri.

For months, they engaged in cybersex with writings and nude photos via Myspace, said prosecutor Yasmin Mullins.

District Judge Leonardo Castro presided over the case argued by attorneys through written briefs two weeks ago. On Monday afternoon, he found LaBlanc guilty and set sentencing for Jan. 10.

LaBlanc's attorney, Jeff Dean, said Tuesday that they will appeal the conviction on grounds that prosecutors didn't prove LaBlanc knew the boy was under 16 and because of problems with the law used to prosecute him.

"It is undisputed that the other person did not tell my client his true age of 15 and that he misrepresented his age as 16," Dean said. "Moreover, it appears from his pictures posted on his profile that he is about 19 or older."

Before the trial, Dean had convinced Judge Joanne M. Smith to stop prosecutors from using a subsection of the statute that says mistakenly believing a child is 16 or older is not a defense.

Dean contends severing part of the law was improper because that violated the legislative intent. He said the entire law should have fallen, with the charge dismissed. He wants the appellate court to consider the law's constitutionality.

"The case has broad implications for any Internet user that seeks to meet another adult online where the conversation might turn sexual," Dean said, noting anyone can be found guilty of a felony, even if they didn't have criminal intent.

"A person will be guilty even when a child misrepresents him or herself as an adult," Dean said. "That the other person honestly and reasonably believes the child is an adult is not a defense and is not even admissible."

Ramsey County Attorney John Choi said the law is constitutional and serves an important public purpose.

"Internet crime against children is something that has dramatic and negative impacts on kids. It's a horrific crime, and it's something that shocks the community's sensibilities and our values," Choi said. "The bottom line is that we did prove the defendant knew the boy was younger than age 16."

Joy Powell • 651-925-5038