Karemera yahoze ari Minisitiri w’Ubutegetsi bw’Igihugu muri Guverinoma yateguye ikanashyira mu bikorwa Jenoside yakorewe Abatutsi mu Rwanda mu 1994. Amakuru avuga ko yaguye muri gereza ku wa Kabiri tariki ya 01 Nzeri 2020.

Mu mwaka wa 2011, Urukiko Mpuzamahanga Mpanabyaha (ICTR), rwamuhamije ibyaha birimo ibya Jenoside, gufata ku ngufu n’ibyibasiye inyoko muntu, ahanishwa igihano cyo gufungwa ubuzima bwe bwose, kimwe na Ngirumpatse Matthieu.

Mu Kiganiro kigufi yagiranye na Kigali Today, Umunyamabanga Nshingwabikorwa wa Komisiyo y’Igihugu yo kurwanya Jenoside (CNLG), Dr. Jean Damascene Bizimana, yavuze ko Karemera ari umwe mu bajenosideri ruharwa, wagize uruhare rukomeye mu itegurwa n’ishyirwa mu bikorwa rya Jenoside yakorewe Abatutsi.

Yagize ati “Yagize uruhare mu ishingwa ry’interahamwe no kuziha intwaro n’imyitozo, gukora ubukangurambaga mu baturage hifashishijwe icyiswe ‘autodefense civile’, n’ibindi. By’umwihariko Karemera afatanyije na Eliezer Niyitegeka, Clement Kayishema, Emmanuel Ndindabahizi n’abandi, ni bo bagize uruhare mu gukangurira interahamwe gukora Jenoside mu yahoze ari Perefegitura ya Kibuye yavukagamo. Ni umwicanyi ruharwa”.

Karemera yafatiwe muri Togo mu 1998 ashinjwa kugira uruhare muri Jenoside yakorewe Abatutsi, yoherezwa mu Rukiko Mpuzamahanga Mpanabyaha rwashyiriweho u Rwanda rwakoreraga i Arusha muri Tanzania.

Mu iburana rye, Karemera yahuriye mu rubanza rumwe na Ngirumpatse Mattieu, Nzirorera Joseph (na we wapfiriye muri gereza mu 2010) ndetse na Rwamakuba André.

Muri 2017, ni bwo Karemera na Ngirumpatse boherejwe gufungirwa muri gereza yo mu gihugu cya Senegal.