LAS VEGAS (KLAS)– The bullet that killed a Las Vegas Metropolitan Police Officer (LVMPD) last week went through the bulletproof vest that was supposed to protect him, investigators said.

Officials cast doubt that any vest would have saved him, yet hundreds of officers in the valley wear that vest every day.

Andrew Walsh, LVMPD assistant sheriff, confirmed during a press conference Monday that the bulletproof vest 49-year-old Truong Thai wore left parts of his body vulnerable to gunfire. The bullet that killed him entered his body through the side of his abdomen, which the vest did not protect.

The vest is similar to those worn by other officers nationwide, according to Steve Grammas, president of the Las Vegas Police Protection Association, the union that represents thousands of active and retired LVMPD officers.

“I don’t know too many vests that will stop a 726 round or a .223 round,” Grammas said. “It’s very tough to cover you totally.”

Bulletproof vests are categorized depending on how much protection against gunfire it has. The standard protection for a vest is considered Level IIIA, says Grammas, which is “tested to stop .357 SIG and .44 Magnum ammunition fired from a longer barrel,” according to the Department of Justice. But, the same vest is not effective against rifle ammunition.

That was the kind of ammunition shot from 24-year-old Tyson Hampton’s gun, Clark County District Attorney Steve Wolfson said outside the suspect’s court appearance Tuesday morning. He describes the AK-pistol hybrid used as a gun meant to “kill a lot of people.”

“I don’t think, with what we saw, a different vest would have played a role. I really don’t,” said Grammas. “An officer can’t go out in full tactical gear like a SWAT guy.”

So why do officers not wear vests with more protection? According to the union president, the extra protection underneath the armpit and side torso “would probably be the most uncomfortable thing that you could (wear), not (able to) put your arms down.” He said it would be ineffective for day-to-day operations as well.

Additionally, he said the kind of gun used in the shooting is not commonly seen on the streets. The possibility of encountering one is always present, he acknowledged, that leaves everyday officers at risk of the same fate as Thai.

”There’s potential for whatever officers are wearing out on the streets not to be enough to protect them?” 8 News Now asked, to which Grammas responded, “absolutely.”

He added that LVMPD officers are responsible for purchasing their own bulletproof vests, as officers hired prior to 2014 are not mandated to wear a vest by the department. Officers receive a yearly clothing allowance that covers the costs of uniforms, vests, and tools each year, though Grammas said the most protective vests on the market can exceed that amount by costing upwards of $1,500.

8 News Now also connected with other law enforcement agencies on their vest policy. The North Las Vegas Police Department said they provide a vest to officers but require them to upgrade it if the officers want to. Nevada State Police said they both purchase and upgrade their officers’ vests every five years. Nationwide, bulletproof vest policies vary by agency