The United States issued a travel warning Wednesday urging any U.S. citizens traveling to Mexico to be cautious. The State Department said those who drink alcohol in Mexico should “do so in moderation” and “stop and seek medical attention if you begin to feel ill.” The statement appeared to refer to the possibility of tainted drinks being served at resorts in the country, according to the Milwaukee Journal Sentinel.

Read: After Woman's Death At Mexico Resort, Tourists Report Similar Instances

“The safety and security of U.S. citizens overseas is one of our highest priorities,” the warning said.

The warning came on the heels of the death of Abbey Conner, a 20-year-old tourist on vacation at a luxury resort in Mexico. Conner and her family were at the Iberostar Paraiso del Mar resort in January for less than a day when she and her brother were found unresponsive in the hotel pool. Conner’s brother Austin survived with minor injuries, but she was in a coma and later died.

Austin admitted the two were drinking, but not nearly enough to cause them to drown in a pool of chest-high water. The Conner family was unsatisfied with the brief and inconclusive investigation done by Mexican authorities — in which only three hotel employees were interviewed.

“It’s all too convenient,” said the family’s attorney, Florentino Ramirez. “If it was an accident, where was everybody? It just doesn’t make sense. There are too many open ends.”

Photo: MexicoVacationAwareness/Maureen Webster

Maureen Webster’s son, Nolan Webster, died more than 10 years ago at a luxury resort in Mexico. Nolan, then 22, was on vacation with his girlfriend when he was found unresponsive in the pool at the Oasis Hotel in Cancun. Hotel officials said Nolan was excessively drunk and his death was ruled by Mexican authorities as a drowning. Despite numerous eyewitness accounts asserting that Nolan did not appear intoxicated, no investigation was ever done.

Read: Family Wants Answers After Daughter's Mysterious Death At Mexico Resort

Since then, Maureen Webster has made it her mission to spread awareness about the dangers of vacationing in Mexico. She started the website MexicoVacationAwareness.com to share her own story and the stories of other families like Abbey Conner’s.

“I was heartbroken,” Webster told International Business Times of the moment she learned of Conner’s death. “I knew — I’ve been running my website for 10 years, trying to scream from the top of any mountain I can find for people to listen. I know the circumstances, the cause and the end result. It’s exactly like Nolan’s story just all over again.”