Trejo was last seen in Las Cruces, New Mexico on April 8, 1986. He was involved in gang activity at the time of his disappearance and was on juvenile probation for a criminal offense. On the day of his disappearance, his family took him to see his probation officer on Solano Drive, south of Apodaca Park. Afterwards, Trejo asked his mother to drop him off at a friend's home at Dona Ana Apartments. Trejo's mother expected him to return to their own residence in the 1400 block of north Tornillo Street that evening, but he never did. When questioned by police, Trejo's friend stated the two of them had gone to Apodaca Park off Madrid Avenue and Trejo went to the toilets at approximately 2:30 p.m. and did not come back. He has never been heard from again.

Trejo was having differences with rival gang members at the time of his disappearance. After he vanished, unidentified individuals called his family to say he had been murdered. His mother suspects his friends knew more about his disappearance than they disclosed. One of Trejo's friends committed suicide after his disappearance and another was murdered. A third friend has left the Las Cruces area.

Foul play is suspected in Trejo's disappearance, but little evidence is available in his case.