Barely two months after Han Junqing, from Beijing, was imprisoned for practicing the spiritual discipline of Falun Gong, he died in captivity. When his family was briefly allowed to see his body, more than a month after he died, his daughter says they discovered it had been sliced open.

“There were stitches at the throat area, using very thick black threads. The incision extended down until covered by the clothes,” said his daughter, Han Yu, at a United Nations event on forced organ harvesting on Wednesday. Her uncle and other relatives managed to unbutton her father’s clothes. “They found that the incision was all the way from throat to the abdomen,” said Han. “When they pressed the abdomen, they found that his abdomen was stuffed with hard ice.” Her father’s organs, she said, had been harvested.

China has repeatedly denied all accusations of organ harvesting and claimed it would stop using organs from executed prisoners in 2015. But, though Han Junqing died in 2004, evidence suggests the practice is ongoing. There are far more organ transplants needed than official organ donors, and the readily available supply of harvested organs is the basis of a massive market.

Official organ donations may come from people who voluntarily choose to donate their organs after death, or people who sell organs such as kidneys. But in June, the China Tribunal, an independent organization created to investigate the alleged crimes, found that some prisoners have their organs forcefully harvested—sometimes while they’re still alive. Human rights lawyers estimate 65,000 Falun Gong practitioners have been killed for their organs since 2001, and members of other religious and ethnic minorities, including Uyghurs, Tibetans, and some Christian sects, have suffered the same fate.

This week, a senior lawyer from the China Tribunal called on the United Nations Human Rights Council (UNHCR) to investigate and take action. “Victim for victim and death for death, cutting out the hearts and other organs from living, blameless, harmless, peaceable people constitutes one of the worst mass atrocities of this century,” Hamid Sabi, counsel to the China Tribunal, told UNHCR.

The organ harvesting contributes to a $1 billion organ market in China, according to the China Tribunal, which attracts both Chinese nationals and people traveling from overseas. A liver can reportedly be sold for $160,000. The large supply of harvested donor organs in China means that there are far shorter waiting times for patients who need donors. In most countries, the limited supply of organ donations means that patients typically wait months or years for a transplant. In China, patients can get an organ in weeks or even days, and so people travel from overseas to take advantage of the market.

“What can legislators and governments do about this?” asked David Kilgour, former Canadian secretary of state for Asia-Pacific and co-author of a 2016 report on organ harvesting in China, at the UN event. Belgium, Italy, Israel, Norway, Spain, and Taiwan have banned organ tourism, making it illegal for their citizens to travel to China for organ donations; Kilgour suggested other countries should follow suit. “If Americans, Canadians, and others showed more commitment to our own values, the dreadful commerce might end quickly,” he said.

Partial legislation from a few key states is not enough, Kilgour added: “The adoption of more comprehensive national legislation against transplant tourism is essential.”

Speaking at the same event, Jiang Li, from Jiangjin district in Chongqing city, shared how her family was persecuted for practicing Falun Gong. Her father, Jiang Xiqing, was put in a labor camp in 2008. “My father was put into a freezer while he was still alive, and his organs were harvested, without the consent of our family,” she said.

The family were permitted to see his body seven hours after his purported death. But when they arrived, said Jiang, they were shocked to discover that his body, which was in a refrigerator, was still warm. They tried to do CPR, she added, but were dragged out of the building and weren’t allowed to see Jiang Xiqing again. Later, they were able to get an autopsy report, which showed his ribs were broken and his organs harvested.