(CNN) -- The container ship Maersk Alabama has seen a lot of drama.
It was attacked in 2009 by four armed Somali pirates, who took the ship's captain, Richard Phillips, hostage on a lifeboat. That gripping tale came to Hollywood in the form of the 2013 film "Captain Phillips."
The ship survived another pirate attack in 2009 and yet another attempt to board the vessel in 2011.
And now: Two former Navy SEALs, hired as security officers on the 500-foot vessel, were found dead aboard.
Seychelles police say the autopsy found the cause of death to be "respiratory failure, with suspicion of myocardial infarction (heart attack)." The presence of a syringe and traces of heroin in the cabin have led to a suspicion of drug use, police said.
More than a week after their bodies were discovered, many questions surround the deaths of Jeffrey Reynolds and Mark Kennedy, both 44 years old. Why did they die together? How did the drugs and syringe get into their cabin? What series of events contributed to their deaths?
Such questions are made more mysterious by friends, family and others who knew the men and told the New York Times that after their years in the military, they had readjusted well to civilian life.
The night before their bodies were discovered, the men went to two bars, followed by two casinos, the New York Times reported, in Port of Victoria, Seychelles. New York Times reporter Ian Urbina told CNN's Brooke Baldwin that according to staff where the men are said to have been on that night out, Reynolds and Kennedy were "outgoing" and "having a great time" and drank tequila shots and vodka with sailors from New Zealand.
"The two (former) Navy SEALs ended up closing that (second) casino and were politely asked to go at the end of the evening," Urbina said.
Surveillance images indicate that they met two women in the hall in front of the second casino and "walked down a dark corridor" with them, Urbina said.
A colleague who had gone to check in with one of the men in a cabin found them at 4:30 p.m. February 18, Seychelles police said.
"It's bizarre. Of course, it's a shock. They're all great guys," said Tom Rothrauff, president of Trident Group, a Virginia-based maritime security services firm that employed them. "I'm absolutely clueless as to what happened."
Although substance abuse is a known problem among veterans, acquaintances of Reynolds' and Kennedy's told the New York Times they were shocked at the idea that either man had used heroin.
"The description of the two men from friends and family was in stark contrast to what sounded like a pretty hard partying night," Urbina said.
A neighbor of Reynolds', Monika Connelly, told the Times that the Reynoldses did not drink alcohol. Another neighbor, Paul Bell, called them "church people."
Both Reynolds and Kennedy had children and "seemed to be family men," Urbina said.
Bodily fluid samples from the two men are being sent to Mauritius for further analysis "to establish if they had consumed a substance which may have induced these events," Seychelles police said in a statement.
Lt. Cmdr. Jamie Frederick, a U.S. Coast Guard spokesman, said the service was investigating the deaths, as required by American law. But he said the deaths "do not appear to be criminal in nature, related to vessel operations, the material condition of the ship or their duties as security personnel."
The ship arrived in the Seychelles on February 16 with a 24-man crew. It was expected to leave two days later.
The Seychelles, an archipelago in the Indian Ocean, has one of the highest rates of injection drug use in the world, according to the United Nations Office on Drugs and Crime (PDF), with 2.3% of the population engaging in this behavior.
Kevin N. Speers, a senior director for Maersk Line, said in a statement that the security contractors boarded the vessel January 29 and that their deaths were "not related to vessel operations or their duties as security personnel."
The Maersk Alabama is "persistently in high-risk areas since she provides feeder service to the east coast of Africa," Speers said in a statement.
"Contracted security is part of anti-piracy protection plans to safeguard crews and vessels," Speers said.
But according to The New York Times, Reynolds and Kennedy told friends that on the open sea, the real enemy is boredom.
CNN's Michael Martinez, Saad Abedine, Khushbu Shah, Tom Cohen and Laura Smith-Spark contributed to this report.