Kenyan prosecutors will on Monday arraign in court three police officers over the killings of a lawyer, his client and their driver, the director of prosecution's office said on Saturday.
Lawyer Willie Kimani and his client Josephat Mwendwa had filed a complaint alleging that Mwendwa had been shot and injured by police in April.
Mwendwa was then charged with a range of offences, including possessing drugs, gambling in public and resisting arrest, rights activists said.
The U.S.-based International Justice Mission, which Kimani and taxi driver Joseph Muiruri worked for, said on Friday their two bodies and that of their client Mwendwa had been found in the Ol-Donyo Sabuk River northeast of the capital.
Police spokesman George Kinoti said in a statement that the three officers had been arrested in connection with the deaths and that an investigation was underway.
"There are three suspects in custody and they will be arraigned in court on Monday," the Director of Public Prosecution said. The statement did not specify what charges they would face.
Rights groups have in the past accused some sections of the Kenyan police of being involved in extrajudicial killings, a charge that police deny.