Cunningham's family said the 35-year-old wouldn't normally leave his dog, Mr. Bojangles, home alone like that.
At his home they found all of his belongings, including his auto and dog.
The Harvard-educated epidemiologist was promoted in July at the US Public Health Service in Atlanta and contributed to responses to outbreaks of Zika, Ebola and health emergencies caused by Hurricane Sandy.
His family, along with the Crime Stoppers of Greater Atlanta, are offering a $10,000 reward for information leading to an arrest in his case. Cunningham's dog, Beau, was also at home.
Addressing conspiracy theories that have circulated since his disappearance, investigators said Cunningham did not work in the infectious disease unit at the CDC.
Timothy Cunningham's father, Terrell Cunningham, said that his son's supervisor said the younger Cunningham reported for work on February 12, but left midday because he wasn't feeling well, according to the Times. But his auto, credit and debit cards, dog, keys, and cell phone have all been recovered, police said, making the disappearance even more eerie.
"My wife and him and swapped phone numbers, Saturday, Tim called over to me from across the way and told me to take his number out of her phone".
The Centres for Disease Control described Cunningham as a "highly respected member of our CDC family", ABC News reported.
On social media, there has been an outpouring of support for the family, and people have been sharing Cunningham's photo in hopes of finding him.
Meanwhile, his mother just wants her son to come home.
The parents revealed they received unusual texts and calls from Timothy the night prior while speaking to Today about their contact with him before.
Cunningham worked in epidemiology, trying to understand health differences across demographics. "He would not be the type of person that, you know, if you kidnapped him and held him, he could give you access to some horrific virus that could be a real problem for the rest of us", O'Connor said.
Her phone was on silent mode. And then he went missing. Upon their arrival, his parents found the house and the garage were locked and two windows were open, according to the Times. "He's worked hard to get where he is", Cunningham's brother, Anterio, said.