The source cautioned that United States officials are counting on Turkish officials to follow through on their end of the agreement, which appears to now be in place with Brunson due to appear before a Turkish court on Friday.
The fourth hearing of the case against Brunson took place in a prison complex near the western Turkish city of Izmir.
Brunson also allegedly had information about a possible coup attempt before July 2016 as one of his text phone messages to a U.S. soldier showed his support for the coup plotters, the indictment said.
Dressed in a black suit, white shirt and red tie, the North Carolina native wept as the decision was announced, witnesses said.
Pompeo said in a speech Wednesday to the Jewish Institute for National Security of America he was "very hopeful that before too long Pastor Brunson will, he and his wife will be able to return to the United States".
After the ruling, Brunson's lawyer said the pastor was likely to leave Turkey.
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Brunson is scheduled to appear in court for a hearing on Friday.
"'Give us the pastor back', they say".
Abdulkadir Selvi, a pro-government columnist in the Hurriyet newspaper whose columns are closely watched for indications of the Erdogan administration's thinking, wrote this week he expected the pastor to walk free and "solve" the Turkey-US crisis.
Turkey had been close to releasing Brunson before amid detention for charges of aiding terrorist groups.
Brunson's lawyer Ismail Halavurt told ABC News they would still move to appeal his case because they reject all the charges.
But analysts warned that Brunson's release alone would not resolve the troubles between Turkey and the United States.
Brunson was arrested and detained for 18 months before finally being charged by the Turkish government with a connection to the coup attempt.
The Turkish government arrested Brunson in October of 2016, claiming he was aiding two groups it considers terrorists - the Kurdistan Workers' Party (PKK) and the Hizmet movement led by USA -based Islamic cleric Fethullah Gülen.
The United States has repeatedly called for his release.
U.S. President Donald Trump, who has imposed sanctions on Turkey in an attempt to secure Brunson's freedom, tweeted: "PASTOR BRUNSON JUST RELEASED". "I am also grateful that President Trump, Vice President Pence, Secretary Pompeo, Ambassador Brownback, Senator Tillis, and other USA officials refused to take "no" for an answer for this man's release". The deal reportedly involves easing economic sanctions on Turkey.
Smith said he had been up all night at home monitoring the court proceedings online, as had at least a few other members of the church's roughly 142,000 congregants.
American officials were quoted as saying that the USA military has a plan to fly the pastor back to America on a military aircraft. In August, the us slapped sanctions on an array of Turkish officials and on some goods, sending Turkish currency into freefall.