Liberian officials say they will prosecute Thomas Eric Duncan, the man infected with Ebola at a Dallas hospital, because he lied at the airport about having been in contact with the disease when he left Liberia, the Associated Press reported.

Duncan had been screened for fever at the airport in Monrovia, Liberia's capital, upon his departure Sept. 19, and showed no symptoms. But according to reports, he was also required to fill out a form like this one:

Here's the health form that #Ebola patient Duncan would have filled out on Sept 19 when leaving Liberia for US. pic.twitter.com/4qlCspMtcR — Geoffrey York (@geoffreyyork) October 2, 2014

According to the AP, Duncan answered "no" to the questions on the form, even though he had recently helped a sick pregnant woman in Monrovia who later died of Ebola.

The New York Times published an account on Wednesday detailing how Duncan helped the woman on Sept. 15. Duncan carried the woman back home after she was turned away from a hospital that had no space in its Ebola treatment ward, the Times reported, and the woman died hours later. Duncan is a resident of Monrovia in his mid-40s.

But it has not been entirely clear whether Duncan knew the woman had Ebola. Some reports have said that her relatives assumed she was suffering from complications with the pregnancy.

A spokeswoman for the consular section of the U.S. Embassy in Monrovia declined to comment to Mashable about Duncan. Asked if there is any kind of screening process in place for Americans traveling from Liberia to the U.S., the spokeswoman, who declined to be identified, said: "There is no screening process." She then hung up the phone.

Duncan "will be prosecuted" when he returns to Liberia, Binyah Kesselly, chairman of the board of directors of the Liberia Airport Authority, told reporters on Thursday.

"We expect people to do the honorable thing," Kesselly said. The agency obtained permission from the Ministry of Justice to pursue the matter.

He said that people like Duncan and Patrick Sawyer, a Liberian-American with Ebola who traveled to Nigeria and infected people there, have brought a "stigma" upon Liberians living abroad.

Duncan is now isolated at a Dallas hospital in serious but stable condition. Texas officials are monitoring about 80 people who may have had direct or indirect contact with him.

Additional reporting by Mashable's Lorenzo Franceschi-Bicchierai and Brian Ries, and the Associated Press