According to official Vatican statements, Estermann and his Venezuelan wife, Gladys Meza Romero, were killed in May 1998 by a young Swiss Guard Cédric Tornay, who later committed suicide. Estermann, formerly acting commander of the Swiss Guard, had been confirmed in his position the same day. Tornay had earlier been reprimanded for breaches of discipline and had been passed over for a medal routinely awarded to Guards after three years of service.
Pope John Paul II personally celebrated Estermann's Funeral Mass in the church of Saints Martin and Sebastian.
Conspiracy theories concerning his death
The homicide has led to theories as to why the murder happened.
- According to the book L'Agent secret du Vatican (2004), by journalist Victor Guitard, Markus Wolf, former No. 2 of the East German secret police Stasi, declared that Estermann had been a Stasi agent since 1979.
- According to a piece edited by Fabio Croce, the three were all murdered by a Vatican killer, due to Estermann's deep knowledge of the small state's trafficks. According to the book Poteri forti by Ferruccio Pinotti, Estermann in 1981 repeatedly travelled to Poland to coordinate the arrival of military equipment from Scandinavia to support the Polish anti-communist organization Solidarity.
- The text Bugie di sangue in Vaticano (1999), written by "a group of Vatican ecclesiastics and lays who cannot continue to avail, with their silence, official truth told by the Vatican", supports the hypothesis that Estermann was the Pope's personal guard, and that he was killed in the course of a supposed struggle between the Opus Dei and masonic parties within the Vatican hierarchy, both attempting to annex the Swiss guard.
- The British journalist, John Follain, undertook extensive interviews with key witnesses to the murders to inform his book, City of Secrets: The Truth behind the murders at the Vatican (2006). Follain dismisses speculation that Estermann, his wife, and Tornay were murdered by an external fourth party or that Estermann was a spy for the former East German government. Follain's research indicated that Cédric Tornay did indeed kill his commander, and his commander's wife before turning the gun on himself. Tornay found the running of the Swiss Guard archaic, and resented the dominance of the Swiss German majority contingent. Tornay turned to Alois Estermann for affection, and enjoyed a short homosexual affair. Their relationship deteriorated into acrimony as Tornay realised that Estermann had betrayed him with another guard. Estermann's close links to the Opus Dei movement, and his final refusal to award the Benemerenti medal for 3-years service led to further frustration and Tornay's ultimate decision to kill Estermann.
- Hanspeter Oschwald: Vatikan, die Firma Gottes., Piper, 1998 ISBN 3-492-03997-9
- Fabio Croce: "Delitto in Vaticano: La verità.", F. Croce Editore, ..., 1999 ISBN
- Thomas J. Reese: Im Inneren des Vatikan. Politik und Organisation der katholischen Kirche., Fischer, 2000 ISBN 3-596-14752-2
- Jacques Vergès & Luc Brossollet: Assassinati in Vaticano., Kaos, 2002 ISBN ...
- Discepoli di Verità: Bugie di sangue in Vaticano., Kaos, 2002 ISBN ...
- I Millenari: Via col vento in Vaticano., Aufbau, Berlin, 2002 ISBN 3-7466-7030-6
- Victor Guitard: "L'Agent secret du Vatican.", Albin Michel, Paris, 2004 ISBN 978-2-226-13804-0
- Valeska von Rogues: Mord im Vatikan. Ermittlungen gegen die katholische Kirche., DTV, 2005 ISBN 3-423-34266-8
- John Follain: "City of Secrets: The Truth behind the murders at the Vatican.", Harper Collins, London, 2006 ISBN ...
- "Strage in Vaticano, un mistero tuttora irrisolto". L'Opinione. 2006-01-16.
- Guitard, Victor. L'Agent secret du Vatican. Paris: Albin Michel, 2004.
- Fabio Croce, Delitto in Vaticano: La verità, F. Croce Editore, 1999
- John Follain, City of Secrets: The Truth behind the murders at the Vatican, Harper Collins, London, 2006
|Commander of the Pontifical Swiss Guard