A Mobile County substitute teacher was arrested Friday after allegations surfaced that she sexually assaulted three teenagers, while assigned to Denton Middle School.

Kristina McMillan Kelly was arrested and charged with two counts of rape in the second degree, two counts of sodomy in the second degree, sexual abuse in the second degree and three counts of a school employee engaging in a sex act with a student under the age of 19.

Detectives were called to the school Friday after a male student reported the abuse to school officials, according to a police statement. Kelly is accused of having sexual contact with two 15-year-old students and a 14-year-old student at her residence on the 1200 block of Barcelona Drive multiple times since January, Rains wrote in an email.

“It (the inappropriate conduct) began in January 2014 and was ongoing until her arrest,” Rains wrote.  Though the alleged abuse began in January, authorities were not aware of it until Friday when the first student came forward.

Kelly has been a substitute with the system since October, said Superintendent Martha Peek. At the time of her hire, Kelly was subjected to the same FBI and ABI background check all county school employees go through, Peek said.

“It’s very thorough,” Peek said. “It’s just as if you go through a police background check.”

It checks for any indication of any problem and checks for any previous criminal activity, Peek said.

“She went through the background check and once she went through it she was an employee,” Peek said.

Peek said Kelly worked sporadically for the system, but she didn’t know exactly how many days she had worked. Kelly had subbed at two schools in addition to Denton, Peek said.

“For the majority of the time she was called to sub at Denton,” she said. “She was only in other schools one day each.”

The superintendent said Kelly was fired on Friday when the allegations first surfaced.

“(Substitute teachers) aren’t permanent employees,” Peek said. “Any indication of a problem like that severs their service with us.”

Peek said the school system has safety policies in place for all types of situations, including situations like this. She reminded staff and students to remain “ever-vigilant” to help promote safety at the schools.

Peek said she was “very proud” of the student who reported the abuse and commended the school officials who acted appropriately once the report was made.

The investigation is ongoing. Anyone with additional information should contact Mobile Police at 251-208-7000, or text to 274637 and include the keyword CRIME 411.