The case of a 22 year-old California woman who died this weekend after receiving silicone injections to the buttocks is just the latest tragedy in a string of illegal cosmetic surgeries that are dominating Hispanic and Brazilian communities, experts say.

Mayra Lissette Contreras is thought to have suffered respiratory failure after alleged "silicone sisters" Guadalupe Viveros and Alejandra Viveros injected large amounts of what they said was silicone into the young woman's buttocks for a fuller shape.

While the sisters claimed to be doctors back in their native country of Mexico, they didn't have a license to practice medicine in the United States. The injections were done in their home, and they reportedly advertised butt augmentation services in flyers that were handed out in public parking lots.

The duo had already been under investigation by local law enforcement after other victims went to police with complaints of being sickened after receiving silicone injections. They were both arrested on June 21st, but released after posting a $20,000 bail -- and have since fled.

Neighbors in the Los Angeles town of Sylmar suspect the two have most likely escaped back to Mexico.

Experts say the red flags were glaringly obvious.

"This poor woman may have been the victim of her own ignorance. Common sense should tell you that something is not right when you're having a medical procedure in some one's home," says Beverly Hills plastic surgeon Dr. Leslie H. Stevens. "A more likely scenario is that the victim knew what she was doing and unfortunately was willing to take her chances."

Silicone is most well-known for its use in breast implants, where the FDA-approved medical grade material is safely encased in a closed shell.

Plastic surgeons stress that silicone should never be injected freely into the body, as it often solidifies into rock-like lumps. It can also be mistakenly injected into a vein that would allow the silicone to rapidly travel to and block the lungs, which is what is believed to have happened to Contreras, pending an autopsy.

There is one FDA-approved exception; a silicone oil called Silikon 1000 has been deemed safe for eye fluid replacement -- but is not used for cosmetic purposes. Some plastic surgeons do use tiny silicone oil droplets off-label as facial injections to prop up pitted acne scars and to flatten wrinkles, but former president of The American Society of Plastic Surgeons Dr. James H. Wells says he doesn't even believe droplet injections are safe.

"I think people should be very, very wary of silicone injections of any kind. There are still some physicians who think facial injections are safe, but I'm not convinced," Dr. Wells tells StyleList.

In fact, it was bad silicone injections that resulted in Priscilla Presley's battle with disfiguring facial lumps and an ensuing lawsuit the celebrity took out against Daniel Serrano, whom she had hired for 'injection parties' with her Beverly Hills celeb friends. The charming South American 'doctor' turned out to have no medical license -- and was found to have injected Presley with the same cheap car-grade silicone that is used by mechanics.

Recent silicone tragedies have dominated the Latin American and South American communities.

The death of former Miss Argentina Solange Magnano this past December happened in much the same way as Contreras. Silicone injections to the 38 year-old's buttocks caused a blood clot to lodge in the model's lungs, and a three-day fight for her life ensued. Magnano finally succumbed to a pulmonary embolism, leaving behind two eight year-old twins.

Experts say it's the cultural desire for a curvier figure that draws these patients in for buttock procedures.

"Patients tend to be Hispanic and Latin American. This is because a fuller, more voluptuous "J-Lo" butt is revered in their culture. In the American culture, a more toned, slender buttock is considered the ideal," says New York plastic surgeon Dr. Jennifer Walden.

In poorer communities, there's less patient education and awareness about how to safely research a cosmetic surgery procedure, which can make people especially susceptible to con artists.

"It keeps happening in minority communities here in California. People prey on their own people. They speak the same language and take advantage of the patient's comfort level," says Dr. Wells.

Indiana plastic surgeon Dr. Barry L. Eppley says there's even a strategy at play.

"Cosmetic charlatans like those two sisters set up shop for about six months until something bad happens, and then they run. The trap is set up from the beginning. They say the procedure is simple and offer a very low cost, and then find people who will bypass anything for convenience and price," says Eppley.

In a similar rash of cases this past March in New Jersey, six women were hospitalized for severe reactions after receiving what was billed as silicone injections to their buttocks. An investigation revealed that they were actually injected with the same thick cement-like goop contractors use to caulk bathroom tiles.

All six women received emergency surgery to remove the hardened caulking from their bodies, as well a strong series of antibiotics. Doctors say they're lucky to be alive.

So why do women keep getting talked into silicone injections? Dr. Eppley says it's the allure of a permanent result.

"There's no such thing as a permanent injectable filler -- even your own fat isn't 100% permanent. Silicone injections are not an FDA-approved procedure anywhere on the body. The only people doing this aren't even on the fringes of the medical world, they're straight-up black marketers," says Dr. Eppley.

As for safe, medically accepted alternatives to enhancing the buttocks, implants similar to breast implants and fat injections also known as the "Brazilian Butt Lift" are today's standard.

Yet outside of Latin American and South American communities, tush enhancements are not popular.

Butt augmentations are the third least common form of cosmetic surgery in the United States, with only 3,900 performed in 2009 at a national average cost of about $4,315, according to the ASPS.

Surgeons cite a high patient dissatisfaction rate due to wear and tear that comes with continually sitting on the implants. Volume loss over time from fat injections as they re-absorb into the body also leaves many patients unhappy.

Yet the desire for other cosmetic procedures like breast augmentation and botox continues to grow in spite of the recession.

Women in search of a sexier figure or younger complexion need to always take the time to do their research, says Dr. Eppley.

"Don't ever put convenience and cost before hiring a fully accredited surgeon and choosing a procedure that is FDA-approved and well within the standard level of care. You could pay for it with your life."

Another alarming plastic surgery trend? Post-divorce "Vengeance" plastic surgery.