The Registrar, Adama Dieng, head of the administration of the tribunal, terminated McDonald's contract following a request from the lead counsel, Gilles Saint-Laurent, according to a decision posted on the ICTR website.
Saint-Laurent had complained of "a loss of confidence and an irrevocable rupture of communication" between him and his assistant.
The two lawyers are members of the Bar of Quebec in Canada, one of the countries which have the most lawyers at the ICTR.
Dieng also ordered McDonald to handover to the lead counsel, within seven days, all original documents in his possession relevant to the Bizimungu case.
The registry, in the meantime, has asked Mr Saint-Laurent to provide it as soon as possible with three candidates from whom a new co-counsel will be designated.
It is not the first time that a lead lawyer has decided to part with his co-counsel. It has also happened that the contract of a defence attorney has been terminated at the request of a defendant.
In addition, the registry can also, on its own initiative, put an end to the services of a lawyer when it considers that he/she no longer respects the signed code of conduct.
All the trial attorneys before the ICTR are paid by the tribunal within the framework of legal aid because the defendants all are regarded as being indigent.
General Bizimungu has been on trial since September 2004 alongside three other officers of the former Rwandan Armed Forces (RAF), including the Chief of Staff of the Gendarmerie during the 1994 genocide, General Augustin Ndindiliyima, who is currently calling his witnesses.
The two generals are on trial together with Major François-Xavier Nzuwonemeye, former commander of the reconnaissance battalion and Captain Innocent Sagahutu, who commanded the elite battalion.
© Hirondelle News Agency