The vacation of a lifetime of two American sisters turned into a tragedy as both were found dead inside their hotel room. The women were identified as Robin Korkki, 42, of Chicago and Annie Korkki, 37 of Denver.

Yahoo! reports that their bodies were recovered last week in the same hotel room of their luxury $2,000 a night resort in the Seychelles, off the coast of East Africa.

The result of the autopsy reveals that the cause for their death is "acute pulmonary edema", known to be a build up of fluid in the lungs. Annie, on the other hand, also suffered a swelling in the brain or "cerebral edema."

"When you are talking about pulmonary edema, that's a really big deal," said ABC News consultant and former FBI agent Brad Garrett. "I would look primarily at drug use directly or indirectly by somebody else."

Their stay at Seychelles, a chain of islands in the Indian Ocean popular for its beautiful beaches and resorts, was part of the sisters' supposed month-long African vacation.

The Korkki siblings worked in banking. The LinkedIn account of Robin shows that she was a commodities trader, and younger sister Annie worked at JPMorgan Chase as stated on her Facebook page.

Moreover, they were both described as "loving sisters and best friends." In fact, they always update their social media accounts about their where-about, specifically their travels to exotic locations. According to ABC News, Annie had also posted photos on Facebook days before the heartbreaking incident.

A statement from the hotel where they booked said that the sisters were discovered "when an employee of their hotel tried to wake them" in their villa.

The day before their bodies were found lifeless, the two had been spotted drinking at the resort until about 6:45 p.m. and were afterwards assisted to their rooms by staff at 8:15 p.m.

Upon the tragic discovery the next morning, on September 22, "no visible signs of injuries were found on the bodies," according to the police report.

"If this is a murder then it is somebody that gave them something," Garrett said. "Based on their apparent health and age, that it's something that they ingested and/or inhaled that caused their death."

Reportedly, medications were found in the sisters' room and have been confiscated to be used as part of the investigation.

ABC News has also confirmed that the mother and brother of the Korkki sisters have traveled to the Seychelles to bring home the bodies of Robin and Annie.