Missing CDC Employee Timothy Cunningham Update: Reward Rises to $15,000 as Family Tries to Remain Positive

The reward for information for the Centers for Disease Control employee who went missing three weeks ago has risen to $15,000 due to donations, an Atlanta police spokesperson told ABC News.

Timothy Cunningham, a commander in the Public Health Service and an epidemiologist at the CDC who worked in public health emergencies like the Zika and Ebola crises, disappeared on February 12 in Atlanta, Georgia. The new reward is a $5,000 hike from last week, marking this the third week Cunningham has been missing.

Cunningham's sister said her and her family are trying to remain "positive and prayerful."

"I have been trying my best to go through daily activities such as work without getting distracted," Tiara Cunningham, Timothy's sister, told ABC News in a text message. "But no one can really prepare you for seeing your face or your brother's face on the news while at work. So it's a new normal that isn't normal and many people won't understand."

Despite the fact that her brother is still gone, she is overwhelmed by the number of donations from family and other private donors to help find for her brother. A GoFundMe page made by friends has raised over $24,300 in the past 15 days to help locate him.

"The support of the public is indicative of how impactful Tim's reach is," his sister said. "He regularly participated in service events around the city. He served citizens in New York City during Hurricane Sandy and was ready to deploy to service in his capacity."

Cunningham, 35, has been missing since the afternoon of February 12. Authorities have said there is no evidence of foul play, but his family said his disappearance is extremely unusual. His wallet with identification cards, cell phone, keys, and his dog were all found in his home.

On Wednesday, investigators announced Cunningham was passed up for a promotion at work right before he went missing.

"He had been informed the previous Monday (before his disappearance) that he was not getting a promotion, but the explanation occurred on the morning of February 12th," said Major Michael O'Connor of the Atlanta Police. "Shortly after the meeting explaining that, he told his supervisors that he wasn't feeling well and decided to go home."

Police also said the Harvard graduate called his mother the morning he vanished but did not leave a message. A witness said she was asked by her husband on Cunningham's behalf to delete his number from their cell phone.

Anyone with information about Cunningham was asked call 911 or the Atlanta Police Homicide/Adult Missing Persons Unit at 404-546-4235.

Missing CDC Employee Timothy Cunningham Update: Reward Rises to $15,000 as Family Tries to Remain Positive | U.S.