On Sept. 15, 2010, Greg Fleniken died unexpectedly in his hotel room in Beaumont, Texas.
There was no sign of a struggle, no obvious injuries to the body and nothing missing from the room. At first, police investigators believed Fleniken died of natural causes.
But a medical examiner ruled Fleniken's death a homicide.
Using photos from the scene of the crime, can you solve the mystery of how Greg Fleniken died?
Watch Greg Fleniken's story on ABC News' "20/20" on Friday, July 4, 2014 at 10 p.m. ET.
|Clue No. 1: The Hotel|
Successful oilman Greg Fleniken often traveled to Texas on business from his home in Louisiana. A man of habit, he always stayed at the Elegante Hotel in Beaumont during his regular trips to the small town.
|Clue No. 2: Security Camera Video|
Footage from the hotel's security camera videos showed that Greg Fleniken entered the hotel at 5:03 p.m. on Sept. 15, 2010.
|Clue No. 3: Cigarettes, Cell Phone and Candy Bars|
According to those who knew him, Fleniken stuck to a routine at the Elegante Hotel. On his bed when he died were cigarettes, his cell phone and candy bars.
"He'd set up, and that was his routine for the evenings," Beaumont Police Detective Scott Apple told ABC News' "20/20."
"He had his phone to communicate with his wife or for business. He smoked a lot, and he had his candy bars because he had a sweet tooth."
|Clue No. 4: Broken Circuit Breaker|
With everything laid out on his bed, it appeared that Fleniken was settling in for the night.
He rented the movie "Iron Man 2" and microwaved popcorn. Because he was watching the movie and using the microwave, Fleniken blew out the circuit breaker and killed power to his room.
The circuit breaker was fixed by a hotel repairman, a registered sex offender. But the repairman had an air-tight alibi after he left Fleniken's room.
|Clue No. 5: Air Conditioner|
When the fuse blew in the hotel, the air conditioner in Fleniken's room had been turned off.
It was never turned on again, leaving the room very hot. According to private investigator Ken Brennan, who was hired by Fleniken's wife, Susie Fleniken, Fleniken "loved the room ice cold. His wife always said that; he liked it like a meat locker."
|Clue No. 6: Lit Cigarette|
The next morning, Sept.16, 2010, Fleniken was found lying dead on the floor of his hotel room between the bed and door. In his hand was a freshly lit cigarette.
Investigators noted that the cigarette was in Fleniken's left hand, even though he was right-handed.
|Clue No. 7: $1,000|
Fleniken lived out of a suitcase when he stayed in Beaumont. His belongings, including more than $1,000, were left undisturbed in his room when he died.
|Clue No. 8: Autopsy Report|
The autopsy report said Fleniken suffered severe internal injuries, consistent with blunt force trauma. His body had broken ribs, lacerations to the liver and scrotum, and a hole in his heart. There was, however, no bruising or any other obvious signs of a beating. The medical examiner listed his manner of death as a homicide.
|Clue No. 9: Indent in the Wall|
Missed during the initial investigation was a small indent in the wall between rooms 348 and 349 that private investigator Brennan and Beaumont Police Detective Apple found later.
Maintenance records show the wall had been repaired, but the indent was still noticeable. The men staying in the room next door had been drinking heavily and told police they didn't have any idea what had happened.
|Solve the Mystery|
There's the evidence. Can you solve the mystery of how Greg Fleniken died?
Tune in to ABC News' "20/20" to find out how Greg Fleniken died on Friday, July 4, 2014 at 10 p.m. ET.