Apparently there is. He is wanted in Liberia on criminal charges; they know he was aware of his lethal condition before he left Liberia.
It is doubtful he will survive to make the trip back, however. The question is, how many other lives will be ruined by his actions?
And Angela Corey "knew" that GZ was guilty as sin. So what? Nobody is guilty of anything until the jury says so. Liberia is simply in a hurry to pin the blame on a single, throwaway guy. They don't want to be pinpointed as a country that executed - perhaps unwittingly - a biological attack on the USA. The prosecutor got the memo and said the words, just as he was ordered to do. It's politics.
Besides, as cynwoody points out just above, the family of the dead girl did their share of lies, otherwise they wouldn't be able to convince the cab driver to transport the patient. As Mr. Duncan quickly went his way, he may have not given it a second thought. Unwise? Perhaps. But all his behavior indicates that he indeed had no clue that he just about killed himself on that day. A person who knowingly came to the USA to get treated would have ran to the hospital right from the airport, as early treatment is more likely to result in survival. As he is now critical... this means that his internal organs are falling apart. There is no cure for that, outside of a transplant. Even if by some magic the virus would disappear from his body right now, it's pretty hard to repair this much damage. Humans can't grow themselves a new heart, or new lungs, or new blood vessels.