Magomed Yevloyev, who ran a Web site on government corruption and police abuse, was shot in the head Sunday in a police car taking him to a station for questioning, the Washington Post reported.
Colleagues of Yevloyev dismissed government contentions that he was shot while struggling for a gun held by an officer, the Post reported.
A posting on Yevloyev's Web site, Ingushetiya.ru, called for a mass protest Monday in Nazran, Ingushetia's main city and the scene earlier this year of violent clashes between anti-government protesters and security forces.
Yevloyev was seized Sunday when he arrived in Ingushetia after spending several months in Moscow.
A passenger on the plane with him told the Post Ingushetia regional President Murat Zyazikov was on the same flight and called police to the airport after recognizing Yevloyev.
Notable deaths of 2014 [PHOTOS]