The family of an American citizen confirmed to The Associated Press the details from a Washington Post report that the citizen has been arrested, tortured and sentenced to 16 years in prison in Saudi Arabia over tweets he sent while in the United States. According to the son of Saad Ibrahim Almadi, a 72-year-old retired project manager living in Florida, he was arrested last November while visiting family in the Kingdom. Almadi’s son said Almadi was sentenced last month.

Almadi is a citizen of both Saudi Arabia and the U.S. State Department deputy spokesman Vedant Patel confirmed Almadi’s detention Tuesday.

“We have consistently and intensively raised our concerns regarding the case at senior levels of the Saudi government, both through channels in Riyadh and Washington, D.C. as well and we will continue to do so,” Patel said. “We have raised this with members of the Saudi government as recently as [Monday] and it is something that we are continuing to pay very close attention to.”

According to Patel, Washington first raised its concerns about the arrested American with Saudi Arabia last December, as soon as it was made aware of the arrest. Patel said the Saudi government offered no information in advance on Almadi‘s sentencing hearing and did not reply to repeated requests by the U.S. Embassy in Riyadh for confirmation of a date. He added a request to attend the hearing was not answered until after it had taken place.

The Washington Post reported Almadi was charged with “harboring a terrorist ideology, trying to destabilize the Kingdom, as well as supporting and funding terrorism.” Almadi’s son said Almadi was detained over 14 “mild tweets” posted on Twitter over the past seven years, mostly criticizing government policies and alleged corruption.

Saudi authorities have tightened their crackdown on dissent following the rise of Crown Prince Mohammed bin Salman. President Joe Biden traveled to the oil-rich kingdom in July for a meeting with Prince Mohammed, in which he said he confronted him about human rights. Their meeting marked a sharp turnaround from Biden’s earlier vow to make the kingdom a “pariah” over the 2018 killing of Saudi journalist and Washington Post columnist Jamal Khashoggi.