He was killed in the church by a masked gunman on November 19, 2009. Sysoev was known for his missionary activity, including among Russia's Muslim community, neo-Pagans, and Protestants. In December 2009, Sysoev's murder was claimed by a militant Islamic group based in the North Caucasus. According to a statement made by Russian Islamists and released on kavkazcentre.com,
Sysoev's sermons were published in a series of books. Explaining the teaching of the Orthodox Church, Sysoev used the term 'Uranopolitism'.
- The New York Times - Russian Priest Killed in Church
- Murder Of Priest Highlights Missionary Role In Russian Church. Radio Liberty
- Islamists claim killing of Russian priest
- Julia Sysoeva: About Fr Daniel, Happiness, Miracles and Martyrdom (in Russian)
- The Final Interview with Father Daniel Sysoev: Hasten to Heaven
- Hieromonk Job Gumerov. Can one consider the death of Father Daniel Sysoev to be a martyrdom?
- Fr Peter Alban Heers - Podcasts on New Martyr Fr. Daniel Sysoev
- 35 Years Of Life. About Fr. Daniel Sysoev Pravoslavie.ru, Dec 21 2009 (in Russian)
- The funeral of Priest Daniel Sysoyev passed in Moscow