MERCEDES – Mercedes police have arrested a third suspect involved in two Rio Grande Valley robberies.

Chief Dagoberto Chavez said one of his investigators used to work as a resource officer for Mercedes Independent School District and he recognized the suspect from a surveillance video.

The suspect, 18-year-old Ernest Sigala, was a student at the same time the officer worked for the district.

The police chief says Sigala was arrested earlier this month in connection to another case.

Watch the video above for further details.