LUFKIN, TX -- A Texas teacher admitted to having sex with four high school students, two at the same time and two others on multiple occasions, school district police said in an arrest affidavit.

Heather Lee Robertson, 38, of Lufkin, Texas, is charged with four counts of improper relationship between educator and student.

According to the affidavit, a Hudson independent school district police officer began investigating the case on April 20, after receiving information about inappropriate relationships between a teacher and several high school students.

One student told police said he had been sexually involved with Roberson for the past few weeks. He said he started chatting and sexting with Robertson through Snapchat shortly after spring break and Robertson asked him to come to her apartment, so they could have sex. He said he was with a friend, another student, and Robertson said it was okay for the friend to come along.

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Both students told police they had sex with Robertson at the same time during the encounter.

The officer then spoke to two other students, who said they had sex with Robertson on a few occasions. They said they would sneak out of their houses and Robertson would pick them up and take them back to her apartment to have sex and then take them back home.

The officer then spoke to Robertson, who admitted to the allegations, according to the affidavit. She said she had recently become a heavy drinker and would sometimes not remember the details of the encounters.

Robertson was arrested Saturday.

Hudson ISD told Crimesider it was not commenting on the allegations. School policy prohibits teachers from having inappropriate relationships with students, reports KTRE.

“School employees are always in the public eye, and the expectation is that they will always observe professional boundaries in their personal relationships with students,” the district’s handbook states.