The first-year teacher worked Fort Stockton High School. She resigned Oct. 22.
Officials at Tom Green County Jail said records did not show whether she had an attorney. A phone listing for Katheryn Steen in Marfa was nonpublished.
The investigation began after school officials started looking into allegations that Steen had recently bought beer for five teenage boys, Fort Stockton police Lt. Louis Hernandez said.
Police investigators found she had been sending adult pornographic pictures in the form of jokes as text messages, he said.
"She was not using her best judgment," said Hernandez, who added that she gave a statement to police admitting she sent the texts.
Steen is charged with selling, distributing or displaying harmful material to a minor, a Class A misdemeanor, punishable by 180 days to a year in jail.
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