LIVINGSTON, TEXAS (CBSDFW.COM/AP) — A Mexican man convicted of killing three teens in El Paso has died of apparent cardiac arrest.

A Texas Department of Criminal Justice spokesman says officials found 49-year-old Ignacio Gomez unresponsive in his cell Sunday morning. He was pronounced dead at an East Texas hospital about an hour later.

Ignacio Gomez (Credit: TDCJ)

Ignacio had been on death row for more than 20 years.

Gomez’s lawyer says he had been diagnosed with schizophrenia and found not competent to be put to death. He did not have a scheduled execution date.

Gomez was convicted in the 1996 shootings of 16-year-old twin brothers and a 19-year-old. He unsuccessfully challenged the conviction claiming police never told him he had the right to legal assistance from the Mexican consulate.

The consulate hasn’t commented on Gomez’s death.

(© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)