The mystery of how a missing CDC worker ended up in a river may never be solved

A Centers for Disease Control and Prevention employee has been found dead nearly two months after he mysteriously vanished, authorities said today.

The body of Timothy Cunningham, 35, was found Tuesday night along the bank of the Chattahoochee River, according to the Atlanta Police Department, after people fishing saw a body and called 911.

There were no signs of foul play and the preliminary cause of death is drowning, the medical examiner said.

The manner of death has not been determined at this time, the medical examiner said.

"We may never be able to tell you how he got into the river," Maj. Michael O'Connor of the Atlanta Police told reporters today.

It's not clear where Cunningham entered the river, which had been previously searched, officials said.

Cunningham, a Harvard graduate, was wearing his favorite jogging suit, officials said. He also was an avid collector of rare stones and had some in his pocket when he was found, officials said.

Cunningham was identified today by dental records, officials said, and the autopsy was completed on Wednesday.

The condition of the body is consistent with Cunningham being gone since Feb. 12, the medical examiner said. The toxicology report is pending.

Cunningham, a commander in the Public Health Service who responded to public health emergencies including the Ebola virus and the Zika virus, disappeared on Feb. 12 after he said he was sick and left his Atlanta office.

All of his belongings, including his dog, were left at his home, according to police and ABC affiliate WSB.

"This is an extremely unusual set of circumstances," Maj. O'Connor told reporters in February.

"The most unusual factor in this case is that every single belonging that we are aware of was located in the residence," O'Connor said. "His keys, his cell phone, credit cards, debit cards, wallet, all his identification, passport -- everything you can think of, we've been able to locate. None of those items are missing."

In March, Cunningham's sister, Tiara, told ABC News that her parents were "remaining positive and prayerful."

"I have been trying my best to go through daily activities such as work without getting distracted," she said. "But no one can really prepare you for seeing your face or your brother's face on the news while at work."