Four Texas residents have been charged with operating a human trafficking ring after an investigation found they had forced more than a dozen women into various computer programming jobs.

Santhosh Katkoori, 31, along with three other people, were charged with second degree human trafficking on July 8, and arrest warrants were issued for all four individuals.

The investigation began in March, when police officers in Princeton, a town located in Collin County, Texas, were dispatched to a house regarding a welfare concern.

During the investigation, police discovered that 15 women were being forced to work for Katkoori and his wife, Dwaraka Gunda, for a series of programming shell companies owned by Katkoori and Gunda. A search warrant of the residence revealed “multiple laptops, cell phones, and fraudulent documents” that were seized and investigated.

According to a Princeton Police Department release, it was later determined the women were being forced to work at multiple locations in Princeton, as well as the nearby towns on Melissa and McKinney.

In addition to Katkoori and Gunda, Princeton police also issued arrest warrants for 24-year-old Chandran Dasireddy and 37-year-old Anil Male.

Further charges remain pending as of July 9.