GRAND RAPIDS, MI - A Lansing man who was a self-styled "slave master" will spend 30 years in federal prison for coercing a teenage girl to send him sexually explicit photos over the Internet.

Ryan Van Stevenson, 33, asked U.S. District Judge Robert Holmes Bell for mercy and fairness prior to sentencing Thursday, June 25, in a letter that said he had strong moral standards before he became involved in an "alternative lifestyle."

Investigators said Stevenson started having online chats with a 15-year-old in Portland, Oregon. They exchanged pornographic images and, over the years, she wrote in her personal diary about her hopes to go to Michigan and be his "slave."

The FBI said the girl wrote: "When it will come down to going to Michigan, being a slave means a ton to me, I can't lose this incredible opportunity. Ryan means a lot to me, Ryan comes first. Always."

When she was 18, she moved to Lansing to live with Stevenson, his wife and their two kids.

Stevenson said "everyone was happy" with the living situation.

"She became part of the family," Stevenson wrote to Bell. "My studies of religion and world culture had given me this false belief that maintaining multiple relationships was acceptable. I know realize I was wrong, and I am truly sorry."

Stevenson pleaded guilty to coercion and enticement of a minor, entering into an agreement that dropped two counts of child pornography. He later tried unsuccessfully to withdraw his plea, claiming he didn't commit the crime. He claimed he first thought the teen was an adult.

"I had no idea that her decision to send explicit photos and my subsequent request for more, was a federal crime," Stevenson wrote.

Last year, FBI agents raided Stevenson's Lansing Taser business, EMD Weapon, 6425 S. Pennsylvania Ave., and found child pornography.

Investigators said Stevenson trolled online message boards and made graphic requests for sexual acts with teen girls. It was on a message board that he came in contact with the victim in Oregon.

The FBI said Stevenson often talked about his desire to be a "slave master" to young women. His vanity license plate read, 1MASTER, according to records.

The victim wrote in her diary in 2012 that she couldn't wait to be Stevenson's "slavegirl."

"I wanna be the best damn slave that he's ever owned. I cannot make master disappointed in me. Hes my whole world. Being his slave is important to me. Its all I think about! He really is the best Master ever. Im so excited to make memories w/him. I hope I can be as pleasing to him in person as well as online stuff," the teen wrote, according to a criminal complaint.

Stevenson's wife told investigators they met when she was 13 in an online chat room, and that he controlled her every move. She dropped out of high school to move in with him. She said he liked "sick and perverted" sexual activity and was violent.

Stevenson referred to himself as the "pillar" of his family as he asked Bell for leniency so he could support his wife and kids.

"The sorrow of being away from my family, missed holidays, missed birthdays and the regret of what happened is almost more than I can bear. There is no chance I will disregard the law in the future, if I am allowed one," he wrote.

Stevenson will spend five years on supervised release after prison. He was ordered to pay $10,875 in restitution.

Angie Jackson covers public safety and breaking news for MLive/The Grand Rapids Press. Email her at ajackso3@mlive.com, and follow her on Twitter.