During the 1994 Genocide against the Tutsi, Nyiramasuhuko lived at her home in Butare.

Witnesses have testified that she supervised roadblocks where Tutsi were intercepted, including one located near her residence.

Historical records indicate that after the killing of Jean Baptiste Habyalimana, the Tutsi prefect of Butare, Nyiramasuhuko called on Interahamwe militia, including those led by her son, Arsène-Shalom Ntahobali, to exterminate all Tutsi in the region.

Witnesses also testified that she ordered the Interahamwe to torture and kill Tutsi civilians, and instructed them to rape victims before murdering them.

In June 2011, the former International Criminal Tribunal for Rwanda (ICTR), based in Arusha, Tanzania, sentenced Nyiramasuhuko and her son to life imprisonment.

Both were convicted of conspiracy to commit genocide, genocide, direct and public incitement to commit genocide, and crimes against humanity, including rape and torture.

They appealed the verdict, and in December 2015 the ICTR Appeals Chamber reduced their sentences to 47 years in prison.

According to reports by the Collectif des Parties Civiles pour le Rwanda (CPCR), an organization that supports the prosecution of genocide suspects, Nyiramasuhuko's name has repeatedly surfaced during Dr. Rwamucyo's appeal hearings, which began on June 9, 2026.

On July 3, a witness who said he had known Dr. Rwamucyo since 1993 told the court he saw him at a roadblock in Butare alongside members of Maurice Ntahobali's family, including Nyiramasuhuko, Shalom Ntahobali, and Chrysostome Nkezabahizi, the then head of the National Office of Population (ONAPO).

The witness testified that Dr. Rwamucyo and the others at the roadblock were wearing military uniforms and carrying firearms, adding that they appeared to be directing the Interahamwe militia responsible for killing Tutsi civilians.

CPCR further maintains that Dr. Rwamucyo had a long-standing relationship with Nyiramasuhuko and notes that his name appeared several times in her personal diary, which recorded meetings and appointments involving the two.

However, on July 7, Dr. Rwamucyo told the court that he did not know Nyiramasuhuko and had never spoken to or arranged meetings with her. He said the only time they crossed paths was briefly at ONAPO offices in Butare.

When questioned about his name appearing in Nyiramasuhuko's diary, he denied that it referred to him, claiming it belonged instead to another "Eugène Rwamucyo from Butare."

Two days later, on July 9, prosecutors pointed out that the telephone number listed next to the name in Nyiramasuhuko's diary matched his own. Dr. Rwamucyo nevertheless repeated that the entry referred to another person with the same name.

As prosecutors continued pressing him about his relationship with the former minister, Dr. Rwamucyo changed his explanation. He argued that there was a reason why his name appeared at the end of the contact list and claimed the handwriting in the diary was inconsistent.
"Why was I added to these diaries?" he asked the court.

Dr. Rwamucyo ultimately acknowledged that the "Eugène Rwamucyo" listed in Nyiramasuhuko's diary was indeed him, but insisted that whoever entered his details into the diary had done so without informing him.