A middle school assistant principal in Poinciana has been arrested over "improper behavior" with a student, the Polk County Sheriff's Office said Thursday. Dr. Keiva Lark, 53, has been charged with lewd/lascivious conduct and a lewd offense against a student by an authority figure. She worked at Lake Marion Creek Middle School.PCSO said the investigation began on April 4 after the principal reported the incident.Lark was placed on administrative leave, pending the investigation, PCSO said. The incident occurred after the victim was sent to Lark's office after throwing balled-up paper across a classroom during a test. "While in the office, according to two witnesses and the victim, Lark told the victim to rub her feet, since he didn't have anything better to do with his hands," PCSO said in a news release. "She removed her shoes and placed her legs across the victim's lap, and he did as he was told."PCSO said Lark was heard scolding the victim for not rubbing her feet correctly, and demonstrated how she would prefer to be massaged, by rubbing the victim's arm and shoulder. A witness heard Lark tell the student to rub her feet like he loved her. A witness also heard Lark tell the victim that she was doing this so he would know what foreplay is for when he gets a girlfriend, PCSO said. PCSO said a witness told detectives that Lark, several days later, told the witness that she (Lark) "crossed the line" during the incident.The victim told deputies Lark has referred to him as "Sexy Chocolate" while passing him in the hallway at the school.Lark initially told detectives that this was only a joke, and that she was just trying to humble the victim, PCSO said. She later admitted that her actions were inappropriate for her profession, but she denied saying anything inappropriate to the victim.>> This is a developing story and will be updated as more information is released