Slain human rights lawyer Willie Kimani and a taxi driver Joseph Muiruri were buried Saturday in their hometowns amid calls for top officials to resign over the killings.
Kimani was buried in his hometown in Kabete, while Muiruri was buried in Kinangop in central Kenya.
The three are alleged to have been killed by Administration Police officers after being abducted on June 23 after a session at the Mavoko law courts. Their bodies were found dumped in Ol Donyo Sabuk River over a week ago.
The late Mwenda, a motorcycle taxi driver, had sought Kimani's help in pursuing charges against a police officer who shot him.
Four police officers are facing murder charges in connection with the deaths.
Isaac Okero, the chairman of Kenya's Bar Association, has called for the resignation of the country's Interior minister Joseph Nkaiessry and police chief Joseph Boinnet.
"What is the cause for the extra-judicial execution? Corruption. If we treat that these things, extra-judicial execution killings will come to an end. We cannot end corruption in the courts or the police force if the vice is rife in Parliament and at the Executive," said Paul Muite, a prominent lawyer and former member of Parliament for Kabete.
Kimani worked in Kenya as a lawyer for the International Justice Mission, a US-based rights group. IJM's Kenya director Claire Wilkinson paid tribute to Kimani in a eulogy at his graveside burial.
"Willie lived up to what he believed in and he fought for it every day," Wilkinson said.
"Our heartbreak at losing Willie is very real and very raw. But Willie has set a fire in us, a fire that is now burning across Kenya, a fire for justice. And it's our responsibility to ensure the fire will not go out," she said.
The killings have sparked days of peaceful demonstrations and a week-long job action by Kenyan lawyers demanding an end to extra-judicial killings that human rights groups say are pervasive.
The lawyers have been boycotting court sessions except for urgent matters.