Defense lawyers for suspended First Vice President Dr. Riek Machar and seven co-defendants on Monday questioned the accuracy of digital hash values presented by a prosecution expert during proceedings at the special court.
The challenge came after the defense asked the court to allow a digital forensic expert to present hash values linked to electronic evidence submitted earlier in the trial.
Hash values function as unique digital fingerprints for electronic files and are commonly used in digital forensic investigations to ensure evidence has not been altered. Algorithms such as MD5 and SHA-256 generate these digital identifiers to help confirm the integrity and authenticity of files.
During the 60th session of the trial at Freedom Hall in Juba, South African digital forensic expert Ratlhogo Peter Calvin Rafadi presented the hash values to the court.
Machar’s lead defense lawyer, Dr. Geri Raimondo Legge, challenged the digital forensic expert, arguing that what had been presented amounted to “mere paper” rather than the underlying hash data.
Legge described hash values as raw digital material extracted directly from devices that contain the original evidence.
“If you click WhatsApp, it will open and you will see the content, even Messenger. These raw materials are always maintained on the original device, whether on a phone, WhatsApp or a laptop,” Legge told the court.
“What has been presented by the witness is just a mere paper, even without any signature, name, date or stamp,” he added.
Legge asked the court to allow the expert to open mobile phones belonging to six of the accused so that WhatsApp chats could be reviewed directly from the devices.
“That is why we asked the court to open the phones of each and every accused person to confirm the content of the device,” he said. “Therefore we reject this piece of paper because it lacks value.”
Lead prosecutor Ajo Ony’Ohisa accused the defense of raising what he called preliminary issues intended to confuse the court and delay proceedings.
“The defense is tactically avoiding questioning the witness on his report, which is already before the court and which they should be addressing,” Ony’Ohisa said. “We ask the court to intervene in this behavior.”
He said the defense’s explanation of hash values was misleading and incorrect, adding that even a layperson using online resources could understand the concept.
Ony’Ohisa said prosecutors had no objection to the defense bringing its own expert to examine the phones and verify whether the hash values would match those presented by the prosecution’s expert.
The prosecutor also noted that the court had previously ruled on the defense request to access the phones of the accused and said raising the matter again undermined the court’s earlier decision.
Presiding judge James Alala Deng adjourned the trial until Wednesday to allow cross-examination of Rafadi to continue.
Machar, 73, and seven co-defendants face charges including murder, conspiracy, terrorism, treason, destruction of public property and crimes against humanity. Machar is under house arrest, while the others are being held at National Security Service facilities in Juba.
The co-defendants are Puot Kang Chuol, 40; Mam Pal Dhuor, 37; Gatwech Lam Puoch, 66; Lt. Gen. Gabriel Duop Lam, 53; Camilo Gatmai Kel, 47; Mading Yak Riek, 45; and Dominic Gatgok Riek, 27.
Prosecutors allege that forces linked to the opposition Sudan People’s Liberation Army-in-Opposition, allied with the White Army militia, killed 257 soldiers from the South Sudan People’s Defense Forces, including commander David Majur Dak, and destroyed or seized military equipment worth about $58 million during an attack on the Nasir garrison in March 2025.