The body of a Kenyan lawyer who was representing a client making a complaint against the police has been found.
The Law Society of Kenya (LSK) said it was a “dark day for the rule of law in Kenya”.
Kenya’s police have often been accused of brutality and they have been blamed for a series of extrajudicial killings.
The police chief has ordered the arrest of three police officers suspected of being involved in his kidnapping.
According to the LSK, Mr Kimani went missing along with his taxi driver and client after a court appointment over a week ago.
One other body has been found but there are conflicting reports as to who this is.
A police source informed a reliable news agency that the two bodies had been found on the bank of a river 70km (43 miles) north-east of Nairobi.
A search is ongoing at the site to find the third body, Kenya’s Standard newspaper reports.
On Thursday, the inspector general of the national police service George Kinoti said that investigations would be pursued.
“In the event that a crime is disclosed linking any person, whether police officer or otherwise, the law will doubtless take its own course,” he said in a statement.
Mr Kimani was working for the International Justice Mission, a US legal charity which focuses on cases of police abuse of power.
He had been representing his client in a complaint against a police officer who had allegedly shot him during a traffic stop in 2015.
LSK says this is the first time that a lawyer working on a sensitive case has gone missing.
However, LSK head Isaac Okero said that the incident suggests “lawyers are becoming a target because of their work”.
In 2011 a Kenyan human rights lawyer accused the Kenyan government of framing him for a bombing to get back at him for defending victims of extraordinary rendition.
Kenyan security forces carried out 25 extrajudicial killing between 2013 and 2015, Kenya’s official rights body said.