EDINBURG – Rio Grande Valley Border Patrol Agents arrested a convicted sex offender on Christmas Eve while he was attempting to enter the United States illegally. During the evening of December 24, agents assigned to the Rio Grande City station working near Roma, Texas, apprehended a male Salvadoran national. The subject was transported to the Rio Grande City station for processing. During record checks, agents identified the subject as Mario Rivera-Perez and discovered a conviction for Sexual Assault of a Child in Chicago, Illinois. The subject also had a previous conviction for DUI and currently has an active warrant from the ...