Pieter Wittenberg, a Dutch humanitarian known for aiding boat refugees on the Greek island of Lesbos, has died at the age of 78. The aid organization Human Power announced his death on Sunday.

NOS reported that Wittenberg had been seriously ill and stopped his public and humanitarian work last month. According to Human Power, shortly after his January acquittal in Greece, he was diagnosed with “a serious, debilitating disease with a likely very limited life expectancy.”

Wittenberg gained international attention for his work helping refugees arriving by boat on Lesbos. He and 23 other volunteers offered water and dry clothing to the arriving refugees. Greek authorities accused them of human smuggling and membership in a criminal organization, arguing that by assisting the refugees they were breaking the law. The volunteers maintained they were saving lives by rescuing people from the sea.

After an eight-year legal battle, Wittenberg and the other volunteers were acquitted in January. A prior charge of espionage had already been dropped. Had they been convicted, they could have faced up to 20 years in prison.

Human Power described Wittenberg as “a man who lived with enormous solidarity for humanity. Someone with a very clear moral compass who knew what he believed was right and acted accordingly.” The organization added that the Drenthe native “found a meaningful path in what mattered most to him: compassion for others.”

In January, Wittenberg reflected on his acquittal, saying it felt “like taking a breath after a long dive.” He said he was “incredibly relieved” but also “empty and sad” over the years of legal pressure and the impact on refugees. He expressed gratitude that the court had “confirmed that helping people is not a crime” but described the damage caused to the refugees as “indigestible.”

Amnesty International welcomed the verdict but said it had taken far too long. The organization stressed that “these charges should never have been brought to trial in the first place” and that the lives of the defendants had been put on hold for many years. Other volunteers acquitted alongside Wittenberg included Syrian swimmer and activist Sarah Mardini and German-Irish rescuer Séan Binder, both of whom were recognized for saving lives at sea.