Tabachnik has an interest in esotericism and spirituality, and beginning in the 1970s he was a member of the Golden Way Foundation and its successor group the Order of the Solar Temple (OTS), run by Joseph Di Mambro.

[2] As a young conductor he was a protégé of Igor Markevitch, Herbert von Karajan and Pierre Boulez, acting as the latter's assistant for four years, mainly with the BBC Symphony Orchestra, London.

[3] In June 1977, having an interest in esotericism, Tabachnik met Joseph Di Mambro, one of the two future leaders of the Order of the Solar Temple, a group notorious for mass suicides and murders in the 1990s.

[4] He had been introduced with his wife Christiane Meylan to La Pyramide, a precursor group, by Nicole Koymans; he joined the next year.

[20][21][22][23] Speaking on his involvement with the OTS, Tabachnik appeared in two 2022 documentary series on the case, Temple Solaire: l'enquête impossible and La Fraternité.

[24][25] Temple Solaire: l'enquête impossible also featured journalists Gilles Bouleau and Arnaud Bédat, both who had accused of him of being involved in the deaths.

[26][27] During an interview for the promotion of the series, Bédat stated he had changed his mind and no longer believed that Tabachnik had planned the deaths, and that him being away in concert had perhaps stopped him from being killed as well.