Transcript for Family searching for answers after daughter dies at Mexico resort
Tonight the U.S. Government warning Americans about allegations of tainted alcohol while traveling in Mexico. As one family suspects, that could have been behind their daughter's death. Here's ABC's gio Benitez. You protect your child from so much since they're born, and you know, it happens in an instant. Reporter: Ginny Mcgowan never imagined she would need to protect her children here on vacation at a five-star resort in Mexico. We're in so much pain and shock and disbelief. Reporter: But then the unimaginable happened. Just hours after the family arrived, 20-year-old abbey conner and her 23-year-old brother Austin were found floating face down in a pool. Austin recovered, but abbey slipped into a coma and later died. Abbey's family now speaking out for the first time. How excited about Mexico were you? Probably the most excited person was abbey. Reporter: The Wisconsin family booked their January vacation at iberostar paraiso resort in playa del Carmen. We said you guys need to meet us in the lobby at 7:30. Reporter: Abbey and her brother Austin stayed around. We swam around for a little bit and decided let's celebrate with a drink. The bartender pours out a line of shots. I take one and everyone else does. And the last thing I remember was just like we are right now sitting here talking and lights went out and I woke up in the ambulance. Reporter: Ginny and her husband ux John, Austin and abbey's stepfather, had been waiting for the kids in the hotel lobby. It was getting close to 8:00. I'm starting to get worried. I said I just -- I need to call their room because I can't contact them any other way to find out where they are. And then she went and got the general manager and quickly brought me to John, explained that there had been an accident. Reporter: The family says a guest found abbey and Austin floating face down in the waist-deep pool. They were then rushed to the hospital. When ginny and John arrived, they found Austin unconscious with a golf ball-sized lump on his head and abbey on a ventilator. Austin was sedated. There was blood on the floor in Austin's room. Abbey really needed to get to an icu. Reporter: By Sunday it became clear that abbey needed to be moved from an icu in Mexico to a higher-level trauma hospital in Florida. When did you realize that nothing could be done? There's a whole protocol. Testshat need to be run. On Thursday they ran those tests, and it was Thursday. That she was pronounced -- Around noon. Reporter: Abbey conner passed away on Thursday January 12th. Mexican officials ruled that her death was an accidental drowning. That day their blood alcohol level was reported to be a .25, three times the legal limit in their home state. Austin says he can't remember how many shots they had. Is it at all possible that this was an accident and that there was just too much alcohol, that you just drank too much? It is a possibility. But every time I think about it, one thought that sticks in my head every time is how if we're in a group of people do two people at the same exact time just pass out in the pool and no one sees it? Reporter: The conner family is now questioning if abbey's death was more than an accident and if Austin and his sister could have been served adulterated alcohol, a toxic mix of cheap indwreents that could include grain alcohol or methanol. Did you think it was just an accident? No. To this day I still don't think it was an accident. Like I said, I've had alcohol before in my life, and I was fine. I know my limit. Reporter: Mexican officials say they've seized 1.4 million gallons of tainted alcohol from Mexican businesses including resorts, clubs, bars, warehouses, and manufacturers in the past seven years. This video is one of the largest seizures in 2015. 260,000 gallons taken from a warehouse in just one day. But the iberostar resort denies evening tainted alcohol, telling ABC news, "We only purchase sealed bottles that satisfy all standards required by the designated regulatory authorities. We are deeply saddened by this incident." The Mexican health ministry tells ABC it has no memories of any adulterated or seized alcohol from iberostar resorts. But just today following our report on "Good morning America" the U.S. State department added a warning about tainted alcohol to its page about travel to Mexico, stating there have been allegations that consumption of tainted or substandard alcohol has resulted in illness or blacking out. If you choose to drink alcohol, it is important to do so in moderation and to stop and seek medical attention if you begin to feel ill. The family has hired an attorney and is suing the resort. It doesn't make sense. You have a standard duty of care to your guests. And to find two of them floating in a pool, it doesn't make sense. Reporter: The hotel insists they did everything they could for abbey and Austin saying in a statement to ABC news, "From the moment in which the guests were found iberostar personnel acted with urgency following established protocols. The hotel's on-site doctor, security personnel, and paramedics immediately responded. Iberostar takes this matter very seriously and has always remained cooperative." Abbey and Austin are not the first people to report having suddenly blacked out after a few drinks during visits to resorts in Mexico. I thought I was dying. Because I couldn't get out of whatever state of mind I was in. You couldn't wake up. I remember thinking how are my six kids going to find out? You know, and what's going to happen to them? Reporter: Jamie and Rick Mallory told the "Milwaukee journal sentinel" their vacation to playa del Carmen almost turned deadly when they say they both blacked out after a few drinks at another resort's beach bar. The next thing that I remember is my husband screaming. I could hear him scream but I couldn't see him. I believe the resorts are trying to hide the fact that the dangers exist. Reporter: Maureen Webster created the website Mexico vacation awareness about the potential risk when traveling to these resorts after her 22-year-old son Nolan's unconscious body was pulled from a waist-deep resort pool and he later died. She says a nurse tried to help her son but the hotel doctor pulled him away saying he was just drunk, which Webster denies. All the cases that I've received on my website, the resorts are quick to blame the guests. So I'm not stopping until something changes. You're starting to hear now from other families who have had issues at Mexican resorts. Yes. Many people. What are they saying? Similar incidents. Incidents of blacking out. Incidents of waking up with injuries. Similar incidents of being required to carry cash to take care of your bills before they even know what the extent of their injuries and treatments are. Reporter: Abbey conner's family telling us they had to pay almost $40,000 in cash in total to get medical treatment that abbey and Austin desperately needed. We ended up using credit cards, calling family, securing it. Reporter: For now a terrible mystery without a resolution. But abbey's family says their suit is not about the money. They say they want other families to know the potential hidden dangers of a vacation in the sun. I wish I could have done something. And I to this day regret it. It will haunt me forever. Reporter: For "Nightline" I'm gio Benitez in piwaukee, Wisconsin.
This transcript has been automatically generated and may not be 100% accurate.