Mass violence is not cheap.

A common misunderstanding is that everything must fail before international crimes — war crimes, crimes against humanity, and genocide — can be committed against civilians. On the contrary, the government, terrorists, or insurgent groups need to coordinate many things to commit atrocities. They need persuasive politics, organized institutions ready to obey orders, and the support of key voters. They need money—a lot.

After another year when the demand for accountability for international crimes far exceeds the supply of justice, July 17 this year—International Day of Justice—is a useful time to emphasize the importance of addressing funding for atrocities. One way is to link the prosecution of mass atrocities with the lucrative transnational crimes that fuel these atrocities.

It is difficult (if not impossible) to think of conflicts in which large-scale atrocities have occurred since the end of World War II but transnational organized crime has not played a role. Transnational criminal activities such as human trafficking, drug trafficking, money laundering, illegal buying and selling of oil, ivory and antiquities have greatly enriched the vaults of war criminals, terrorists and genocide.

Consider some examples. The notorious Lord’s Resistance Army (LRA) is a rebel organization operating in large areas of Central Africa. Since the outbreak of war with the Ugandan government in the mid-1980s, it has committed a series of war crimes and crimes against humanity. In recent years, due to the illegal trafficking of ivory through Sudan, the Lord’s Resistance Army has been able to survive and continue to kidnap children to participate in the fighting.

In Syria and Iraq, the Islamic State of Iraq and the Levant (ISIL) has been charged with all documented international crimes, including attempts to genocide the Yazidis. ISIL’s economy relies on transnational organized crime, including the illegal sale of oil through Turkey and international markets. Although ISIL’s destruction of cultural preservation sites has aroused great media attention, ISIL has also retained some cultural relics in order to sell them illegally on the black market. Such transnational crime allows ISIL to survive — and terrorize civilians — as long as it exists.

In rare cases, the link between illegal and profitable crime and mass atrocities has received the attention of the courts. In 2012, former Liberian President Charles Taylor was convicted and sentenced to 50 years in prison for aiding and abetting war crimes and crimes against humanity in Sierra Leone. The core of his conviction was Taylor’s involvement in the “conflict diamond” trade to fund insurgent groups that threatened civilians in Sierra Leone.

Recently, the Kosovo Expert Chamber and the Expert Prosecutor’s Office were established, and many hope that it will reveal whether the Kosovo Liberation Army was engaged in human organ trafficking after its war and the alleged anti-ethnic cleansing campaign against Serbia in the late 1990s and early 2000s.

All these examples show that the perpetrators of mass atrocities are also involved in profitable transnational organized crime. Given the complexity and difficulty of meaningful accountability for large-scale atrocities, and the slow pace of international criminal justice, it is time to consider paying more attention to investigating the perpetrators of international crimes because of their involvement in illegal trade networks.

More work can and should be done to undermine funding for the perpetrators of mass atrocities. This requires the joint efforts of national institutions and international organizations such as the International Criminal Court (ICC) to link the investigation of transnational organized crime and international crime. Some progress has been made in this regard, and countries like Uganda have established special departments capable of investigating these two types of crimes. Others promised to do the same. Former International Criminal Court prosecutor Fatou Bensouda has proposed investigating human trafficking in Libya as the specter of crimes against humanity, although so far there is no evidence that specific actions have been taken in this matter.

One promising approach is to ensure that investigators investigating large-scale atrocities are better able to gather evidence of transnational organized crime. If they are unable to use the evidence to establish their own case, they should share it with countries and institutions that are capable of doing so and can therefore disrupt illegal networks. Countries should also explore the possibility of establishing a permanent international tribunal dedicated to dealing with transnational organized crime, perhaps in conjunction with efforts to establish an international anti-corruption court.

Every year, transnational organized crime generates hundreds of billions of dollars. But this is not just in dollars and cents. It is at the cost of human life. Therefore, combating such illegal crimes helps protect civilians from violence and atrocities. This has been done before.

In the early 20th century, few gangs were as infamous as Al Capone. It is generally believed that Capone was responsible for multiple murders and violent crimes and was eventually convicted of tax evasion. Detaining “Scarface” in a crime that is easier for him to be prosecuted means that he is not on the street and no longer poses a direct threat to society. In other words, putting Capone in jail for tax evasion prevented his ability to commit violent crimes in the future.

This is also a commitment to link the investigation and prosecution of large-scale atrocities with transnational organized crime. Disrupting illegal trade networks and prosecuting perpetrators of transnational crimes will weaken the ability of genocidal regimes, terrorist organizations, and rebel groups to fund their violent activities, thereby deterring atrocities.

Follow the money, and perhaps the perpetrators of atrocities around the world will meet their opponents.

The opinions in this article are those of the author and do not necessarily reflect the editorial stance of Al Jazeera.