O'Connor said the one thing he still doesn't understand is how Cunningham ended up in the river.
The manner of death has not been determined at this time, the medical examiner said. During a news conference on February 27, police said they have "no reason" to believe the missed promotion had anything to do with his disappearance.
"We found that to be an unusual circumstance in a missing persons case", Major O'Connor told reporters at a press conference on Thursday afternoon.
A body found in the Chattahoochee River has been identified as missing CDC worker Timothy Cunningham, CBS News affiliate WGCL-TV reports.
Anxious neighbors formed search teams in effort to find 35-year-old Timothy Jerrell Cunningham who was last seen February 12th. Police said there did not appear to be foul play, but they are awaiting a toxicology screen and other testing results.
Maj. O'Connor said he was wearing his favorite jogging shoes at the time he was found and three crystals were in his pocket.
On Tuesday night, fishermen called 911 after discovering a body in the river.
The case perplexed investigators because Cunningham's keys, cell phone, credit cards, debit cards, wallet and all forms of identification were found in his house, along with his beloved dog.
When they arrived at his house a few days later, Cunningham's parents said, they knew something was wrong because his Tibetan spaniel was unattended.
"We may never be able to tell you", he said, noting there wasn't any surveillance footage in the area that would help piece together his final movements.
Cunningham's father told The New York Times in February that he'd been anxious about his son recently because he didn't seem like his usual self in conversation.
Cunningham, a commander in the Public Health Service who responded to public health emergencies including the Ebola virus and the Zika virus, disappeared on February 12 after he said he was sick and left his Atlanta office. His sister, Tiara Cunningham, the last family member who spoke with Cunningham before he disappeared, said she felt lost without her brother.
A Morehouse College and Harvard University graduate, Cunningham has played a pivotal role in addressing past public health emergencies - including the Ebola and Zika viruses.