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Three prominent senators excoriated the U.S. Air Force on Tuesday for its failure to report a military conviction of the Texas gunman who massacred 26 parishioners and they called for a comprehensive probe into the blunder.

Sens. Richard Blumenthal, D-Conn., and Kirsten Gillibrand, D-N.Y., said they have sent letters to Secretary of Defense James Mattis urging him to conduct a widespread investigation on the military's reporting compliance.

Sen. John McCain, R-Ariz., also said he will push for oversight hearings looking into the Air Force's conduct.

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The senators, who serve on the Senate Armed Services Committee, which has jurisdiction over the Department of Defense, said the 26-year-old gunman, Devin Patrick Kelley, would not have been able to buy guns and slaughter innocent parishioners if the military had complied with the law.

"Twenty-six wonderful people might be alive today if the law had been followed by the United States military — and this heinous crime committed by the Texas shooter while he was still in the military — had been reported," said Blumenthal.

An Air Force officer failed to enter Kelley's domestic violence court-martial into a national gun-check database that would have barred him from buying weapons, the Air Force said on Monday.

Air Force brass ordered a full review of how the service handled Kelley's conviction at the general court-martial, and the lawmakers want a broader investigation to make sure other convictions are not slipping through the cracks.

"I wrote to Secretary Mattis yesterday asking him to do an investigation to make sure there are no other cases like this," Gillibrand said. "To actually do an audit of anybody who was convicted of violent felonies, anyone who would be ineligible to purchase a firearm, to make sure that information is getting to the Depart of Justice and the FBI."

McCain, who chairs the Armed Services Committee, called for the Pentagon to improve training and said he will call an oversight hearing soon to get to the bottom of the lapse.

"What happened?" he asked. "Why something like this could take place?.. Yes, we will be holding them accountable."

In 2012, Kelley was convicted at a general court-martial on two charges of assault, according to the Air Force. A retired Air Force colonel who supervised prosecutors said Kelley was convicted of fracturing his baby stepson's skull and assaulting his first wife, at Holloman Air Force Base in New Mexico.

Kelley opened fire on Sunday at First Baptist Church in Sutherland Springs, Texas. A Glock and a Ruger handgun were discovered inside a Ford Expedition where Kelley's body was found after a chase following the shooting and a Ruger AR-556 rifle was recovered at the church.