(CNN) Sheikh Salman al-Awda waited at his Riyadh home for Prince Mohammed bin Salman. It was 2012 and the charismatic preacher received the then 27-year-old prince with little fanfare.

"We didn't think the visit was a big deal," recalled Awda's son, Abdullah Alaoudh, a Washington-based legal scholar at Georgetown University. "He was just a regular prince."

Despite his obvious ambition, bin Salman was considered a political novice. His father was the governor of Riyadh and not yet king, and, in the eyes of the country's political class, he was just another member of Saudi Arabia's thousands-strong royal family. The prince who would later become known by his initials, MBS, appeared enthusiastic about Awda's ideas for change in Saudi Arabia, according to Alaoudh.

In this meeting and at least two other meetings to come -- including one in the royal court alongside the future King Salman -- Awda, who was 55 at the time, extolled the virtues of reform and inclusive governance, according to Awda's son.

Five years later, King Salman appointed his son as the Crown Prince. Three months after MBS was promoted, Awda was arrested as part of a crackdown overseen by a security agency established by the newly-anointed heir to the throne.

Awda and his son, Abdullah Alaoudh. Alaoudh is a legal scholar at Georgetown University where he regularly speaks out about his father's case.

After a year of pre-trial detention, in September 2018, Saudi Arabia's General Prosecutor presented Awda with a list of 37 charges and recommended the death penalty. This Sunday, the cleric will return to court, where the judge may decide on whether to make a ruling in the case, and if found guilty, sentenced, according to his family.

The cleric has spent nearly two years in solitary confinement, his son told CNN. For the first few months of his detention, "his legs were shackled and he was handcuffed. The prison guards used to throw his meals at him," said Alaoudh.

Awda was held incommunicado for the first six months of his arrest. When his family was finally allowed to visit him, he told them that he was frequently deprived of sleep and food, Alaoudh added.

He eventually signed documents, likely forced confessions, that he could no longer understand because of his poor mental and physical state, according to his son. His father told the family that he "signed some documents but had no idea what they said."

Saudi Arabia has frequently been accused of making prisoners sign confessions under duress

Alaoudh's blood pressure shot up, and so did his cholesterol levels. He was hospitalized for a few days, according to his son. "It felt to him like a slow death," said Alaoudh.

Prince Mohammed bin Salman met with Salman al-Awda before the royal was elevated to Crown Prince.

When the United Nations raised concerns in 2017 that torture had been used to obtain confessions, the Saudi government responded with a letter denying the claims.

According to the charge sheet, Awda's confessions related to his activism in favor of a constitutional monarchy, and his alleged association with high-profile members of the Muslim Brotherhood.

Saudi authorities did not immediately respond to CNN's request for comment about the charges made against Awda.

From radical preacher to social media star

Awda's 2017 detention wasn't his first. Early in his career, Awda aligned himself with the kingdom's much-feared Sahwa (The Awakening) movement. They were the so-called Islamic revivalist clerics credited with ushering in ultraconservative religious policy in the late 1970s. In the 1990s, Awda was one of the most high-profile Sahwa clerics to rally for the expulsion of American troops who arrived in the kingdom during Iraq's invasion of Kuwait. He railed against the monarchy in his sermons, and in 1994, he was arrested on charges of inciting rebellion against the kingdom.

In 1999, Awda was released, and appeared to have undergone a personal transformation. He began to speak publicly about the merits of political reform, religious tolerance, pacifism and combating corruption. He condemned the September 11, 2001 attacks in New York while most other high-profile clerics were muted in their responses. In 2008, he hosted a popular TV show on Saudi television.

During the 2011 Arab Spring , the kingdom's monarchy began to eye the cleric with suspicion again. Awda had come out in support of the uprisings that swept the region. In the kingdom's predominantly Shia eastern province, protesters were taking to the streets. In neighboring Bahrain, Saudi forces quashed a pro-democracy uprising that all but paralyzed the island kingdom. Awda was unrelenting in his support for Arab democracy.

Awda and his daughter, whose face has been blurred.

He took to social media, accumulating 13.4 million Twitter followers, and prolifically posting videos. No longer the firebrand cleric, the middle-aged preacher preferred to speak casually into a phone camera.

Murdered Saudi government insider-turned-critic Jamal Khashoggi once called the preacher one of "the most beautiful examples of (personal) transformation."

"Look at Sheikh Salman (al-Awda) today," Khashoggi said in a televised interview. "This beautiful, creative cleric who gathers young people and ushers them into the world."

In interviews, Awda said he owed his ideological transformation to the many books he read in prison.

But in early September 2017, the cleric's social media accounts went silent. According to his family and activists, a Saudi government official had called the preacher, instructing him to tweet an endorsement of the kingdom's still-nascent embargo on neighboring Qatar

The preacher responded by tweeting a prayer for reconciliation "between the peoples." According to his family, he was arrested less than a day later.

By the time Awda was arrested, Khashoggi was already in self-imposed exile, fleeing the government's attempts to silence him.

"If I hadn't, with so much pain in my heart, left Saudi Arabia, it is possible that I would have been banned from travel," said Khashoggi in an interview with al-Sharq, "Or else, if I was so unlucky, I would have been with Sheikh Salman al-Awda and other prominent figures who have been jailed."

Death penalty met with condemnation

Saudi activists and Alaoudh believe that the cleric had long drawn the ire of MBS. The prince cared little, they argue, about getting Awda's help with his reform agenda. He was more interested in having the cleric rally his large audiences on the prince's behalf.

"(MBS) was just trying to familiarize my father with him as part of his efforts to introduce himself with the public and influential figures," said Alaoudh.

"Sheikh Salman is not someone who can be controlled."

Sheikh Salman is not someone who can be controlled. Abdullah Alaoudh

The charges Awda faces consist primarily of his support for the 2011 Arab Spring. The prosecutors accused Awda of having ties with the Muslim Brotherhood, designated a terror organization by the kingdom in 2014. He was also charged with "criticizing the kingdom's decision to boycott Qatar," according to the charge sheet reviewed by CNN.

In one of his lectures, Awda denied belonging to the group, but said he didn't believe that the group was a terror organization.

The prosecutors pointed to a series of meetings organized by Awda in Gulf Arab countries called the "Renaissance Summit," around the time of the Arab Spring, describing them as hosting seditious discussions by "intellectuals."

Saudi prosecutors did not accuse the cleric of acts of violence or incitement to violence. And reports that Awda would face the death penalty were met with condemnation by international rights groups.

The US State Department mentioned Awda's case in its 2018 International Religious Freedom report published last month, while the United Nations Human Rights Office of the High Commissioner criticized his arrest in a January 2018 statement about the Saudi crackdown.

Asked if Awda's family expected the cleric to be executed, Alaoudh said hopes for his father's release began to dim after Khashoggi's October 2018 murder. He echoes Saudi activists who say that anything is possible.

"With the current mentality, do I think that it is far-fetched that MBS can execute my father?" said Alaoudh. "Not really."