Ilya Segalovich, Yandex Co-Founder & CTO, Brain Dead & In Coma

Ilya Segalovich, Co-Founder & CTO of Russian search engine Yandex, has lapsed into a coma and is brain dead. Segalovich, 48, had been responding well to cancer treatment before unexpectedly succumbing to complications early this morning, according to a statement released by the company.

Yandex listed him as dead; many news reports initially reported that he died, as did our original story. He’s not expected to recover, once life-support machines are turned off.

Segalovich co-founded Yandex more than 20 years ago, building the company into one of the world’s largest search engines. By some measures, Yandex is one of the top-five global search engines, even nudging out Microsoft’s Bing in total number of searches.

Yandex is also the dominant search engine in Russia, with more than 62% of the country’s search market according to LiveInternet. In recent years, Yandex has been expanding its presence with its global, English language search engine Yandex.com, as well as regional versions in Belarus, Kazakhstan, Russia, Turkey and the Ukraine, with more countries in the works.

Yandex went public in March of this year. Segalovich planned to donate proceeds from his shares in the company to charity, including Maria’s Children, a fund founded by Segalovich’s wife, Maria Yeliseyeva. Maria’s Children uses arts therapy to help in the social, psychological and intellectual rehabilitation of orphans and special-needs children. Yandex is also a majority investor in U.S. based search engine Blekko.

Search Engine Land columnist Andy Atkins-Kruger, who knew Segalovich personally, is planning a longer tribute to the search pioneer over the weekend.