Lawyer Willie Kimani, his client Josephat Mwenda and driver Joseph Muiruri's genitals were crushed before the three men were killed.
Andrew Kanyi, a pathologist and forensic specialist representing the victims and the Law Society of Kenya, presented an autopsy report in court Wednesday. The report indicated that some body parts of the three were seriously injured.
Appearing before Justice Luka Kimaru, Dr Kanyi said the three died of similar circumstances.
"After we carried out an autopsy of Kimani, 32, we documented 14 injuries which were very extensive," he said.
He told the court that the cause of death was head injury.
"Some deaths can be painful because according to the autopsy, the three could have been tortured and brutally beaten before they were killed," said Kanyi.
He said Muiruri could have died under similar circumstances as Kimani but his body appeared to have been tied since there was an indication of lack of oxygen, the report added.
"Muiruri had his wrists bound with a sisal rope and the same rope was used to tie the ankles together," Kanyi said.
The external findings, according to the doctor, were that blood was oozing from the nose and mouth.
He added that there was an armband around the left wrist with colours of the Kenyan flag and name Muiruri written on it.
The doctor said there was a bruise on the left cheek and a complex ligature mark and bruise around the neck.
"Muiruri's body was identified by his brothers and sisters and other members of the family before an autopsy was conducted," Kanyi said.
When the body was recovered, Muiruri was dressed in a black sweater and white boxer shorts, which had blood stains.
"He had worn a checked multi-coloured shirt extensively torn on the left side and with two buttons," said Kanyi, adding that there were bruises on the testicles and the brain was mixed with blood.
LSK lawyer Charles Kanjama had requested the court to allow Kanyi present his report even if he had not sworn an affidavit.
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He said it was the jurisdiction of the court to respect some parts of their application order, which included obtaining evidence of the disappearance of the three and the circumstances in which the bodies were found.
"The court had ordered that the postmortem be conducted in the presence of a representative of LSK to confirm the results," Mr Kanjama added.
He said families of the three could receive justice if the pathologist did not present his report.
On July 5, a postmortem performed by Chief Government Pathologist Johansen Oduor indicated the bodies were found in a river in Ol-Donyo Sabuk, Machakos County.
In his report, Dr Oduor said Kimani was hit on the back of the head several times and his skull was fractured. Muiruri was strangled and had injuries on the head believed to have been caused by a blunt object. The case will be heard on Tuesday next week.