Juvenal Kajelijeli was born on 26 December 1951 in Rwinzovu, préfecture of Ruhengeri, in Rwanda. From 1998 to 1993, he held the position of mayor in the Commune of Mukingo, was re-elected in June 1994 and remained in this position until mid-July 1994. As such, he represented the executive branch of power at a communal level. He was in the position to exercise authority over his governmental subordinates and could requisition the police of the commune. However, even during the period when he was not the elected, mayor, a superior/subordinate relationship existed in effect between Kajelijeli and the Interahamwe (extremist Hutu militia) of the Mukingo and Nkuli communes.
From 1991 to July 1994, he was considered to be one of the leaders having control over a group of Interahamwe in the Mukingo commune. From 1992, he was said to have actively participated in their military formation and training in this same commune. Moreover from 1993, under his instructions, this group was fitted out with uniforms and by the 7 April were said to have received arms from him for use in carrying out the massacres. Moreover, he was also said to have wielded his influence over the Interahamwe of the Nkuli commune from January to July 1994.
Following the death of President Habyarimana, on the evening of 6 April 1994, Kajelijeli, was said to have presided over a meeting in the canteen situated next to the Offices of the Nkuli Commune, during which he was reported to have delivered a speech inciting the audience – composed uniquely of Hutus – to eliminate the Tutsis. He was said to have promised them arms to mount an attack on the following day.
On the morning of 7 April 1994, he was said to have assembled units of the Interahamwe at the Byangabo market and to have given them the order to kill and exterminate the Tutsis. He was also said to have publicly incited the group to commit genocide against the Tutsi population. He was reported to have himself taken part in this attack, notably by transporting the Interahamwe militia and stacks of weapons between the Mukamira camp and the sites of the killings.
From the 7 April 1994 he allegedly ordered, organised and supervised different attacks against and massacres of Tutsi civilians in their homes or in the places where they had sought refuge in the communes of Mukingo, Nkuli and Kigombe. He was said to have taken part personally in carrying out these attacks. Furthermore, a large number of the assailants (the Interahamwe from the communes of Mukingo and Nkuli) were under the effective control and authority of Kajelijeli, and he reportedly undertook no measures whatsoever to prevent or put an end to these acts. Moreover, he was accused of having procured weapons with which the Interahamwe could carry out attacks against the Tutsis.
In addition, according to a report published by FIDH and Human Rights Watch in 1993, Kajelijeli was reported to have been implicated in massacres of the Bagogwe people (a group of sheep farmers from North West Rwanda related to the Tutsis) at the beginning of 1992.
In mid-July 1994, confronted with the advance of the troops of the RPF (Rwandan Patriotic Front – an opposition movement composed essentially of Tutsi refugees and led by Paul Kagame), Kajelijeli fled Rwanda in the direction of the Democratic Republic of Congo. On 5 June 1998, he was arrested in Benin.