On April 9, Chinese political prisoner Guo Hongwei, 48 and serving a 13-year sentence in northeastern Jilin province, died under mysterious circumstances. The “crime” he was in prison for: supporting Hong Kong democracy.

Authorities took Guo to the Guowen Hospital in Jilin with a brain hemorrhage, after his family repeatedly warned that his high blood pressure had gone untreated, reports Hong Kong’s pro-democracy Apple Daily.

His father suspects foul play—for good reason. Guo was transferred to Gongzhuling Prison from Songyuan Prison last year, after Guo’s family accused officials there of torturing him.

“We are not convinced,” his father told Radio Free Asia. “He mustn’t be cremated until the cause of death is known. There needs to be due process, and [the cause of death] must be identified. He was persecuted [to death]. Not allowing a critically ill patient with systolic blood pressure of 260 out on medical parole is the same as killing him.”

Another source told RFA that Guo Hongwei was tortured in prison, kept in a 6.5-feet-square cell with no toilet, lights or ventilation. The source added that Guo “already had high blood pressure when he went in, so his chances of surviving such an environment weren’t good.”

Chinese officials remain characteristically uncooperative. They’ve refused to answer any questions or let the family take pictures at the funeral. They also won’t release his body to his loved ones.

But there’s not really much Chinese officials can say for themselves: Guo’s death seems the result of standard prison operating procedure, especially for political detainees.

His courage in speaking out against Communist Party abuses had repeatedly gotten him trapped in the system’s clutches. In 2003, he reported that Xu Wengui, an official at the local state prosecutor’s office, was embezzling state funds, whereupon Guo was arrested and sentenced to five years in prison. The trumped-up charge: “embezzlement of funds,” one frequently used against whistleblowers.

After his release, Guo launched a campaign against the practice of torture in Chinese prisons. He boldly went to Beijing with his mother to petition the Ministry of Justice to investigate the abuses of power and to compensate him for his suffering.

In response, unknown thugs beat him and his mom and the state declared his demand for justice and recompense to be “blackmail and extortion.” After he staged a public rally in support of democracy in Hong Kong, he and his mother were both sent to prison, in March 2015, the mother for six years—and when his sister spoke up for him, she was sent to prison for more than five years on charges of “picking quarrels and stirring up trouble,” a favorite claim of the Communist Party.

In Beijing, Guo had joined with other human-rights activists to fight for democracy during Hong Kong’s 2014 Umbrella Movement—the activism that, two years later, led to the 13-year sentence that finally led to his death in custody.

As the group Chinese Human Rights Defenders noted, “Guo Hongwei’s death follows a similar pattern of detainees and prisoners of conscience being tortured to death while in custody in China, where the accused officials who have engaged in torture and officials responsible for the deaths have largely enjoyed total impunity.”

CHRD called on Chinese authorities to cooperate with an investigation and to prevent the destruction of evidence. But such cooperation will never happen in Communist China.

So here’s what those of us in the Free World do: We don’t let the party get away with such atrocities. We remember those who have been tortured or disappeared or imprisoned simply for trying to live freely. Remember Guo Hongwei. Don’t forget his name. Remember his courage in willingly confronting, time and again, a regime that had already imprisoned and beaten him. And let’s once and for all disentangle our economic affairs from that of this monstrous regime.

Beijing can jail bodies, but it can’t put memories under lock and key.

Elisha Maldonado is a member of the New York Post editorial board and a senior fellow for the Independent Women’s Forum. Folllow her on Twitter: @ElishaMaldonado