A requiem mass for slain lawyer Willie Kimani, his client Josephat Mwenda and a taxi driver, Joseph Muiruri is being held at the Consolata Shrine in Westlands, Nairobi.
Kimani and the other two were kidnapped and then killed and their bodies dumped in Ol-donyo Sabuk River.
According to a pathologist report, Kimani was beaten up several times at the back of his head by assailants before being strangled to death. When his body was found, he was still tied with a rope.
On the other hand, the taxi driver was first strangled and then beaten on the head with the same blunt object. The results, released on Monday, indicated that Mwenda had severe bleeding in the neck, chest, and a fracture on his head.
The autopsy was carried out at Kenyatta National Hospital by government pathologist, Johansen Oduor accompanied by other specialists.
Four police officers Fredrick Leliman, Stephen Chebulet, Silvia Wanjiku and Leonard Maina Mwangi are being detained over the killing of the three.