Daniel Timothy Duplaisir, 37, pleaded not guilty in a Houston federal court to charges of using an under-age girl's pictures on the internet to extort money from a Texas A&M University professor, James Arnt Aune.

Aune, head of the Department of Communications at the University, later committed suicide as a result of the threats by jumping from the roof of the campus parking garage, January 8. He was 59.

U.S. prosecutors allege that Duplaisir, who was arrested in January, took pictures of a young female relative, Karen McCall and used her to lure Aune into a sexually explicit online relationship.

Duplaisir, claiming to be the girl's angry father, then sent Aune threatening text messages and emails demanding $5,000 for his daughters' counselling by Jan. 8, 12:00 p.m.

Duplaisir also blackmailed Aune that he would approach university officials if he failed to give the money.

An extract of the threatening text message by Duplaisir sent on January 7:

"If I do not hear from you I swear to God Almighty that the police, your place of employment, students, ALL OVER THE INTERNET...ALL OF THEM will be able to see your conversations, texts, pictures you sent."

A federal judgeTuesday ordered Duplaisir to remain in jail, he was not allowed any bond. He will go on trial beginning May. 28. If convicted, he will face a maximum of two years in prison.

An excerpt of the email by Aune to the girl:

"Your Dad texted me ... and then called me and told me he was going to turn me into the police. I answered and said I would do whatever he wanted. I sent him $1,000 and then promised more."

He also wrote a letter to the girl's father minutes before his death.

"Killing myself now And u will be prosecuted for blackmail."

Duplaisir, since 2011 has been luring and blackmailing random men into a sexual online relationship by clicking naked pictures and videos of a young relative and then calling his targets pretending to be the girl's outraged father.