TAMPA — Police say Alexandro Garibaldi shot his cousin to find out if a vest the men thought was bullet resistant would actually stop a bullet.

But it turns out there was little to no chance the camouflage vest Joaquin Mendez slipped on Saturday night would have saved him from harm because the vest was a fragmentation protective vest, also known as a flak jacket, Tampa police said Monday.

Flak jackets are a form of body protection meant to stop fragments from high explosive weaponry such as grenades. They are not designed to stop a bullet. Police had initially reported that Mendez, 23, was wearing a bullet-resistant vest but after further investigation determined it was a flak jacket, police spokesman Steve Hegarty said.

The bullet pierced the vest and Mendez's upper body. He died at a local hospital. Garibaldi, 24, was charged with manslaughter.

BACKSTORY Police: Tampa man killed in attempt to see if bullet-resistant vest worked

Hegarty didn't have more details about the vest, such as where it came from and how old it is. But flak jackets are outdated pieces of equipment that were replaced decades ago by more advanced body armor that can stop bullets, said Rod Havens, a tactical gear expert at the Brandon Army-Navy Store.

"They don't use them anymore," Havens said of the military and flak jackets. "Why would they? They're three times as thick as modern body armor and hardly do anything."

The term "flak jacket" dates back to World War II but later versions, such as those used by U.S. soldiers in the Viet Nam war, used DuPont's Kevlar fabric. They were designed to stop shrapnel, not bullets.

"Those flying bits of metal don't carry the mass that a bullet does, so they're easier to stop," Havens said.

By the time of the first Gulf War in the early 1990s, U.S. troops were wearing more advanced Kevlar vests that can stop bullets. Vests can be bolstered with ceramic or steel plates capable of stopping large-caliber rifle rounds. The vests have also become standard issue for law enforcement agencies.

According to police, Mendez and Garibaldi apparently thought the vest they had was capable of stopping bullets.

A witness told investigators that Mendez sat in a chair outside a home at 2407 E. Gordon St. and put the vest on, wondering aloud whether it worked. At that point, the witness said, Garibaldi took out a gun, said, "Let's see," and shot.

Officers responded minutes after the shooting. They said they found Mendez outside with a bullet wound in his upper body. Inside, they found blood and the vest, which had a bullet hole.

Police said Garibaldi told investigators he heard a gunshot, then discovered his wounded cousin outside.

Mendez died at a local hospital. Garibaldi was charged with manslaughter with a weapon and being a felon in possession of a firearm. He remained in the Hillsborough County Jail late Monday in lieu of $20,000 bail.

Both men had seen the inside of the county jail before.

Garibaldi pleaded no contest in Hillsborough County last year to discharging a firearm in public and obstructing an officer. In a separate case, he pleaded guilty to possession of a controlled substance without a prescription and marijuana.

Last month, Mendez was found guilty of misdemeanor marijuana possession and sentenced to time served. The court withheld judgment on a cocaine possession charge and gave him 18 months probation and 50 hours of community service. On Aug. 6, he was arrested and charged with driving under the influence. That case was still open at the time of his death.

Reached by phone Monday, Mendez's mother passed the call to a family member who said the family was in too much pain to comment. A Gofundme page set up for the family has raised at least $6,200 of a $10,000 goal.

"Your departure drags our hearts with you," the page says in Spanish. "You have been a part of all of the happy days we've lived. Now you've gone and we can't find the way to calm the anguish that consumes us."

Monday afternoon, a group of the men's friends gathered at a makeshift memorial on the waterfront near Desoto Park, just east of the home where the shooting happened. Rap music blared from a car's speakers as they drank beer. Someone had placed an unopened can next to a framed photo of Mendez perched on the retaining wall and flanked by a few dozen prayer candles.

The men declined to comment, saying they wanted to respect the family's privacy. But as they loitered there, they spoke about withholding blame and judgement, and about mourning the loss of two friends, not just one.

Times senior news researcher Caryn Baird contributed to this report. Contact Tony Marrero at tmarrero@tampabay.com or (813) 226-3374. Follow @tmarrerotimes.