The U.S. Department of State is urging the Venezuelan government to respect human rights following the arrest of opposition leader Manuel Rosales shortly after landing in his home country. Rosales’ arrest follows the conviction of another opposition leader, Leopoldo López, currently serving 13 years in prison for allegedly inciting violence by organizing protests against socialism.

“We are making a call to the Venezuelan government to respect due process for Rosales and for all those in prison for changes with political motivation,” said State Department Spokesman Mark Toner on Sunday, “The Venezuelan government has the obligation of respecting human rights and the fundamental liberties guaranteed by international law.” He noted the United States’ “concern” for Rosales arrest.

Rosales, the former governor of Zulia state, had been in exile in Peru for six years before returning Thursday. Following a presidential campaign bid against late dictator Hugo Chávez, Rosales was charged with embezzlement and other corruption charges in 2008. He fled the country for six years before returning on Thursday. Many doubted he would do so until he posted a photo of himself on Twitter holding a plane boarding pass, reading “I have my boarding pass now. I am going to my beloved land. Chinita bless Venezuela,” the latter a reference to the Virgin Mary.

Upon landing in Venezuela on Thursday, Venezuelan Secret Police (Sebin) officers apprehended him and are now keeping him in a detention facility. Rosales had intended to run in the nation’s parliamentary elections in December. He is being held on charges of “illicit enrichment,” according to Venezuela’s Attorney General office. His trial will begin on November 12, state officials announced today. Colombian station NTN 24 notes that Chávez had vowed to imprison Rosales by any means necessary. “I am dedicated to imprisoning Manuel Rosales,” he said in 2008. “Enough! He will be in jail, know it in Zulia and all of Venezuela, because scum like that has to be in jail, not governing a state.” The A New Time Party (UNT), of which Rosales is a member, has issued a statement condemning those who have accused Rosales of “returning to Venezuela to divide the opposition” and calling the charges against him “pure lies.” Carlos Rosales, Manuel’s son, has told media that he will begin organizing rallies and prayer vigils for his father, asserting that the charges are politically motivated and false. He will also set up a mailbox for supporters to send him prayers and good wishes, and described his father as “emotionally calm” in face of his arrest. In addition to receiving support from his faction of the opposition, Leopoldo López himself has issued a statement from jail in support of Rosales. “I extend my solidarity to Manuel Rosales… no matter how many assaults and arbitrary actions [they take], they will not be able to deter the change the people demand. Strength!”

Lopez, the leader of the Popular Will anti-socialist party, is serving a 13-year sentence for organizing a peaceful rally against President Nicolás Maduro, an act labeled “terrorism” by the Venezuelan government. Following his conviction, the U.S. State Department issued a statement saying the White House was “deeply troubled” by it and “have underscored our concern with the charges brought against Mr. Lopez—which we consider illegitimate—and we have repeatedly called for his release and for the release of all Venezuelans who are imprisoned for political reasons.”

The Obama administration labeled Venezuela a “national security threat” in March 2015 for its violent crackdowns on opposition leaders, extending sanctions to a number of military and Sebin officials.