The cause of his death is stated as renal failure. He celebrated his final Mass on 22 March at the Comboni College chapel and that afternoon felt feverish. He went to bed with the nuns being notified of his condition since he and others believed he had contracted malaria. His fever was high and the treatments for his condition began on 23 March though he had been pessimistic about his chances since he knew his condition would become serious. The sisters grew worried on 24 March since he had been vomiting though the night of 26–27 March grew even worse. Sister Romilde watched over Ambrosoli during that night though the morning on 27 March saw his condition collapse at an alarming rate. Sister Romilde gave him medicine in drip doses while the priest asked for Father Marchetti to hear his confession before he died. He felt somewhat better around 5:00am and confided to Sister Romilde that he had a few hours left to live though was content and said of it: "Be it God's will". Over the next several hours the distance between breaths lengthened and soon his breathing ceased as his heartbeat slowed. He died at 1:50pm. His niece Giovanna graduated a week after her uncle's death. Cardinal Gianfranco Ravasi praised Ambrosoli for his "faith in Christ and of Christian love to which he had consecrated his entire existence". The beatification process passed its first hurdle after the forum for the local process was moved on 16 April 1999 from Lira (where the late priest died) to Gulu. The cause commenced under Pope John Paul II on 17 July 1999 after the Congregation for the Causes of Saints issued the edict declaring "nihil obstat" (no objections to the cause) and titled Ambrosoli as a Servant of God. John Baptist Odama inaugurated the diocesan process of investigation in Gulu on 22 August 1999 and later closed the investigation on 4 February 2001 before all documents were to be sent to the C.C.S. in Rome for further investigation. But this could not happen until another process was held in Como which Renato Corti oversaw from 7 November 1999 until 30 June 2001. The C.C.S. validated these processes on 4 June 2004 and received the Positio dossier from the postulation in 2009 for investigation. The nine theologians issued unanimous approval for the cause at their meeting at 5:00pm on 4 December 2014. The congregation's Promoter of the Faith Carlo Pellegrino chaired the meeting of the theologians and referred the cause to the cardinal and bishop members of the congregation for their decision.