A 57-year-old Superior man faces nine felony charges for allegedly soliciting sex from a 14-year-old girl on Facebook.

Authorities said Robert Louis Carlson spent a month planning the encounter, sending the girl numerous sexually explicit messages and photographs before arranging to meet up with her in the Gary-New Duluth neighborhood on Tuesday.

A criminal complaint indicates police were alerted to the messages at some point and took Carlson into custody when he arrived for the meeting. It was not disclosed how or when investigators first learned of their communications.

Carlson was arraigned Thursday in State District Court in Duluth on nine counts of solicitation of a child to engage in sexual conduct through electronic communication. Each charge carries a maximum sentence of three years in prison.

"While the defendant does not have a criminal history, the content and sheer number of explicit messages communicated to the minor are indicative of the risk the defendant poses to public safety, namely minor females," St. Louis County prosecutor Kristen Swanson wrote in a memo to the court.

Sixth Judicial District Judge Theresa Neo set Carlson's bail at $10,000 with conditions or $75,000 without. She also ordered him to have no unsupervised contact with anyone younger than 18.

According to the complaint:

Carlson began messaging the girl Feb. 2. When the minor said she was going shopping with her mother, Carlson asked if they planned to go to Victoria's Secret as "there would be a lot of stuff" for her at that store.

Over the course of the conversation, the girl revealed her age, to which he replied: "Oh, wow. Only 14." He went on to describe that as "way too young," but continued to communicate, asking the girl to send photos of her new clothes.

"Make sure nobody finds out," he wrote at one point. "We both will get in big trouble."

Carlson reached out again the following day, telling the minor he kept looking at the photos and describing her new underwear as "very sexy." The defendant began making sexually explicit comments and sent her a nude photo.

On Feb. 5, Carlson began inquiring about meeting the girl for sex, making several explicit suggestions and saying he would pick her up and find a place to go.

Carlson reached out to the girl from a different Facebook account Feb. 27, saying his first account had been disabled. He expressed concern the girl's mother had found out about their messages, which the girl said was not the case. Carlson then asked to continue the conversation via text message because he didn't want to write "inappropriate things" through Facebook.

Carlson went on to tell the girl that they would have sex in his truck and that he had found "the perfect spot." He suggested they go to Superior because it is more secluded.

In later messages, Carlson said he was cleaning out his truck. He also told her: "I have been thinking about if we are still meeting each other in the spring and summer, we could do it outside."

On Monday, Carlson told the girl he was prepared to meet the next day.

Carlson was arrested at their meeting spot shortly after 4:30 p.m. Tuesday. In an interview, Carlson admitted to sending the messages and arranging to meet with the girl for sex, but stated that he "wanted to get to know her more first."

The case was investigated by members of the Duluth Police Department's Sex Crimes, Abuse and Neglect Unit and the Lake Superior Forensic Technology and Internet Crimes Against Children Task Force, which is housed at the Superior Police Department.

Carlson is scheduled to be back in court March 26.