Mokhtar Belmokhtar, the elusive leader of al-Qaeda in Africa, has avoided capture by the U.S. military and its allies since 2003. Last year, U.S. authorities announced they had targeted Belmokhtar in an airstrike in Libya. But eight months later, officials still question whether he truly died in the attack.

The “pirate king of the Sahara” has been the mastermind been the mastermind behind some of the most prominent attacks in northern Africa. Here’s a quick look at who he is:

What is his background?

Born in Algeria and trained in Afghanistan, Belmokhtar rose to prominence through his prolific smuggling and kidnapping. After joining al-Qaeda’s faction in North Africa, he broke off twice – forming new splinter brigades, the most recent of which is known as al-Murabitoun.

At 43, he financed his operations by his elaborate network of smuggling cigarettes, drugs and diamonds across the Sahara.

Which attacks is he associated with?

Belmokhtar’s followers are linked to multiple kidnappings and guerrilla attacks. Some of the biggest include:

Attack on a hotel and café in Burkina Faso’s capital, 2016. Gunmen stormed a hotel in Ouagadougou after sunset, taking more than 100 people hostage. At least 23 people were killed in the attack, including one American missionary.

Attack on a luxury hotel in Mali, 2015. In a joint attack by three terrorist factions, the seven-hour standoff at the Radisson Blu Hotel left at least 20 people dead, one of whom was a U.S. citizen.

Killing hostages at an Algerian gas plant, 2013. The four-day attack killed at least 38 foreign hostages, three of them Americans. Militants seized the plant and targeted foreign workers. The event prompted U.S. officials to charge him in federal court.

Kidnapping two U.N. workers in Niger, 2008. Two Westerners were working in Niger when they were taken by Belmokhtar and his militants. After being held captive for four months, the workers were released in Mali, according to the FBI.

Why is it so hard to confirm his death?

In countries such as Yemen, Pakistan and Libya, where the U.S. government has little or no military footprint and only limited intelligence visibility, it’s difficult or impossible for U.S. personnel to access places where such attacks take place. That means they can’t scour those sites for physical evidence or obtain DNA samples. In some cases, the local government can’t or won’t access such sites either.

Without physical evidence, American officials must rely on clues gleaned from intelligence to determine whether a target was killed.