(CNN) The man accused of opening fire in an El Paso, Texas, Walmart, killing 22 people and wounding several others, has been indicted on a capital murder charge, the El Paso County District Attorney's Office said following the grand jury's Thursday decision.

District Attorney Jaime Esparza intends to seek the death penalty in the August 3 massacre, according to a statement.

"The District Attorney's Office will continue to work hard to ensure that justice is done and is committed to assisting the victims through the judicial process," the statement said.

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Capital murder is the highest charge in Texas, Esparza's office said, and is punishable by death or life in prison without parole.

In the days after the deadly rampage, suspected gunman Patrick Crusius of Allen, Texas, was placed on suicide watch based on the recommendation of medical staff, El Paso County Sheriff's spokeswoman Leslie Antunez told CNN on Tuesday.

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