McALLEN, TEXAS (ValleyCentral) — The investigation started with a series of Instagram messages.

In May, someone using the name “Aubry” contacted a 21-year-old McAllen woman on Instagram, calling her “promiscuous,” according to McAllen Municipal Court records. The messages also contained information about the woman’s location, which made her “believe she is being followed.”

Gilberto Luna. (Photo courtesy of the Hidalgo County Sheriff’s Office.)

The woman, who had attended Sharyland Pioneer High School, suspected a former Pioneer High School teacher, Gilberto Luna, 35, of Alamo, had sent the messages.

They had a sexual relationship when she was a senior and Luna was a teacher, according to court records. Officers arrested Luna in August and searched his iPhone.

“The cellphone data extraction also showed the Instagram account (Aubry) linked to Mr. Luna’s cellphone,” according to the affidavit, “labeling him as the owner of said account.”

Officers also discovered that Luna had “maintained access” to the woman’s social media, email and iCloud accounts, which allowed him to access her personal information and track her location.

Gilberto Luna. (Photo courtesy of the Hidalgo County Sheriff’s Office.)

“We’re going to have to wait in order to verify the validity of their evidence,” said attorney Lennard K. Whittaker of McAllen, who represents Luna. “And the methods by which they acquired the evidence.”

Along with the “Aubry” account, the McAllen Police Department found photos of Luna and the woman “engaging in sexual conduct,” according to court records. Some of the photos had been taken in November 2018, just months after the woman turned 17 years old.

Luna was charged with improper relationship between educator and student, a second-degree felony. The charge, however, was dropped because the statute of limitations had expired.

Officers arrested Luna again on Aug. 14, when he was charged with possession of child pornography, a third-degree felony.

After reviewing the information from his phone, Luna was arrested for a third time on Nov. 2. Officers charged him with stalking, a third-degree felony.

If convicted on either the child pornography charge or the stalking charge, Luna faces a maximum of 10 years in prison.