Martti Ahtisaari, Finnish Nobel Peace Prize Winner, Dies at 86

The United Nations appointed Mr. Ahtissari commissioner and special representative to Namibia in 1977, beginning the long and tangled trail that led to the country’s independence 13 years later. In 1991, he took over as head of Finland’s Foreign Ministry. As war raged in the former Yugoslavia, he became chairman of an international panel focusing on bringing peace to Bosnia-Herzegovina.

While he had spent most of his career as a diplomat, he entered the political fray in 1994, when he was elected as Finland’s President, serving a single six-year term. A strong supporter of the European Union, he oversaw his country’s entry into the bloc in 1995, months after Finnish voters had approved membership in a referendum.

Up until the election campaign, his political reputation had been unsullied. But, as he sought the presidency on behalf of the Social Democratic Party, Mr. Ahtisaari faced — and denied — critics’ assertions that he had struggled with alcohol abuse and had taken a double salary from the Finnish foreign ministry and the United Nations for his mediation efforts in Bosnia.

Even as president, he continued as a peacemaker, negotiating to end fighting in Kosovo in 1999.

After he stepped down as president, Mr. Ahtisaari he founded the nonprofit Crisis Management Initiative, which helped promote peace in the Indonesian province of Aceh, where, for 29 years, insurgents from the Free Aceh Movement fought for independence from the government in Jakarta.

Under a peace treaty signed in Helsinki, the Finnish capital, in 2005, the rebels agreed to drop their demands for full independence in the province, which has vast reserves of oil, natural gas, timber and minerals, and settle for broad autonomy in return for the withdrawal of some Indonesian security forces.