Atlanta(CNN) The CDC worker who was missing for nearly two months before his body was found in a river in Atlanta died of suicide by drowning, the Fulton County Chief Medical Examiner Dr. Jan Gorniak told CNN Wednesday.
Timothy Cunningham, 35, was last seen on February 12. His body was discovered in the Chattahoochee River in the northwestern part of the city on April 3.
In April, police said there were no indications of foul play in his death.
Authorities made a positive ID of the remains by using dental records, Gorniak said last month.
Cunningham's disappearance prompted a high-profile police search and a $10,000 reward for clues. As days went on, internet rumors circulated that the case was tied to his alleged role as a flu vaccine whistle-blower at the Centers for Disease Control and Prevention. The rumors were debunked by police and his family.
In April, Maj. Michael O'Connor of the Atlanta Police Department said Cunningham's home is not far from the river. Cunningham was also known to be a jogger, and was wearing his "favorite jogging shoes" when he was found.
According to O'Connor, Cunningham was also an avid collector of "crystals," and three were found in his pocket.
The condition of the body is "consistent" with Cunningham having been in the river since he first went missing, Gorniak said. There were no signs of trauma on the body.
"We may never be able to tell you how he got into the river," O'Connor said.
Cunningham was last seen in mid-February, shortly after a CDC supervisor told him why he was being passed over for a promotion, police have said.
The CDC's director issued a statement in March denying that Cunningham hadn't gotten a promotion and noting that he'd been promoted in July. Atlanta police responded by doubling down on their version of events, citing the CDC as the source of the information.
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.
Co-workers told authorities that Cunningham had been "obviously disappointed" on the morning of February 12, when he learned why he wasn't getting the promotion he'd hoped for, police have said. He left work quickly, saying he felt ill, they said.
Earlier that morning, at 5:21 a.m., Cunningham's mother had received a text message from him, she has said. "Are you awake?" her son asked. But her phone was on silent mode. "I wish I had that opportunity to answer that text," she said later.
Cunningham also called his mother at 9:12 a.m. that day, but she did not answer, Atlanta police have said. He did not leave a message.
Cunningham was a highly respected epidemiologist at the CDC, having risen through the ranks to become a team leader in the US Public Health Service Commissioned Corps. He earned a spot last year in the Atlanta Business Chronicle's 40 Under 40 list, a who's who of the city's young standouts.
The CDC called him "invaluable" to the agency's work.
"Tim's impact will be felt not only through his significant contributions to CDC's mission, but also through his influence on the lives of his colleagues and friends," the statement said.
With more than 16 years of experience in public health, he'd co-authored 28 publications on topics ranging from sleep deprivation to pulmonary disease, with a special focus on how health issues affect minorities. He worked on public health emergencies including Superstorm Sandy, the Ebola outbreak and the Zika virus.
Friends said Cunningham was smart and caring, with a big grin and big hugs to match.