Dr Tim Cunningham left work because he was feeling unwell. No one has seen him since. 

It was Monday the 12th of February when Dr Tim Cunningham was told by his supervisor that he would not be granted the promotion he was hoping for.

The Harvard-educated scientist, who works for the US Center for Disease Control and Prevention in Georgia, was disappointed.

Shortly after the meeting, Cunningham told his supervisor that he was feeling unwell, and would be going home.

No one has seen him since.

Police have referred to Dr Cunningham’s disappearance as occurring under an “extremely unusual set of circumstances,” with a number of strange events taking place in the weeks prior.

The 35-year-old had called in sick to work on Thursday, February 8th, and Friday, February 9th – the two work days preceding his Monday meeting.

Terrell Cunningham, the epidemiologist’s father, told police that on Sunday the 11th,: “Tim had been in communication with us extensively… there were some exchanges via phone as well as text that alerted me to be concerned about our son.”

Dr Cunningham sent a text message to his mother, Tia-Juana Cunningham at 5:21am on Monday with the question: “Are you awake?”

Her phone was on silent – a decision she is now berating herself for.

There was also an unusual conversation with a neighbour, Chris Torry, that police are trying to make sense of.

Torry told Fox 5 Atlanta that his wife and Dr Cunningham had swapped numbers at some point. On Saturday, Dr Cunningham requested that his wife “take the number out of her phone.

“It seemed a little strange,” Torry remarked.

When Dr Cunningham’s parents could not get in contact with him on Monday evening, or the days following, they grew worried.

His father told NBC it was out of character for him not to respond to calls from family members.

The Cunningham’s decided on February the 14th to travel from their home in Maryland, to Dr Cunningham’s home in Riverside, Atlanta. When they arrived, their concern turned to fear, as his house contained all his personal belongings, including his wallet, mobile phone, car keys, credit cards and passport.

Despite the house being locked, the windows upstairs were open, which again was something his parents could not make sense of. Dr Cunningham was usually highly vigilant when it came to home security.

They were also alarmed that Dr Cunningham’s pet dog, Mr Bojangles, had seemingly been left with no food or water. This was something their son, who loved his Tibetan spaniel more than anything in the world, would never do.

Dr Cunningham, a commander in the US Health Service Corps, who has worked on public health emergencies like the zika and Ebola viruses, has now been missing for more than two weeks.

Since his disappearance, theories about his whereabouts have begun to surface online.

One conspiracy theory suggests, according to News.com.au, that Dr Cunningham was “set to warn the public about the alleged dangers of the flu shot”.

There is no evidence whatsoever to support that theory, especially given he was an avid supporter of vaccination.

Alternate theories suggest he is preparing to execute a biological terrorist attack, given his thorough knowledge of diseases, with another purporting Dr Cunningham has been kidnapped due to his understanding of viruses.

All claims have been vehemently denied by his family and friends, and have no factual basis.

His mother has desperately appealed to her son, “Tim, if you see any of this information please know that you can come back home.

“We love you and miss you.

“We just want you back in our arms.”