A 57-year-old Superior man admitted Wednesday to soliciting sex from a 14-year-old girl through Facebook.

Robert Louis Carlson pleaded guilty in State District Court in Duluth to three counts of solicitation of a child to engage in sexual conduct through electronic communication.

Authorities said Carlson spent a month sending the girl numerous sexually explicit messages and photographs before arranging to meet up with her in the Gary-New Duluth neighborhood in March. A criminal complaint indicates police were alerted to the messages at some point and took Carlson into custody when he arrived for the meeting.

Carlson was originally charged with nine counts of solicitation. The remaining charges were dismissed under the terms of a plea agreement with the St. Louis County Attorney's Office.

Prosecutor Kristen Swanson said Carlson will be required to register as a predatory offender, but he would not be sentenced to any further jail time under the agreement.

Carlson, who has no apparent criminal history, may also argue for a stay of imposition, which would allow the convictions to be deemed misdemeanors if he successfully completes probation.

Sixth Judicial District Judge Theresa Neo ordered a presentence investigation and psychosexual evaluation ahead of an Aug. 12 sentencing date.

According to the complaint:

Carlson began messaging the girl Feb. 2. Over the course of the conversation, she 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, eventually sending numerous sexually explicit comments and nude photographs.

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

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 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 March 5, Carlson made plans to meet the girl the next day. He was arrested when he arrived at their designated spot.

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.