The death of Albert Ojwang was the latest incident to draw scrutiny of Kenya's security services after years of extrajudicial killings and disappearances that Ruto has repeatedly promised to stop in the face of rising public anger.

Police say Ojwang, 31, was arrested in western Kenya on Friday for allegedly defaming the country's deputy police chief online, and died "after hitting his head against a cell wall".

His wounds, including a head injury, neck compression and soft tissue damage, pointed towards assault as the cause of death, according to pathologist Bernard Midia, who was part of a team that conducted an autopsy.

The death of Ojwang, who wrote about political and social issues, has drawn widespread condemnation from rights groups and touched off protests outside the mortuary where his body was examined in the capital Nairobi.

"This tragic occurrence, at the hands of the police, is heartbreaking and unacceptable," Ruto said in a statement.

"As we mourn his passing, let us patiently but vigilantly follow the progress of the investigations without making premature judgements or drawing conclusions."

The Independent Policing Oversight Authority (IPOA), the police watchdog, has launched an investigation and on Wednesday named five police officers who arrested Ojwang in Homa Bay County and escorted him to Nairobi's central police station.

Two days later, on June 8, police took him to hospital where he was declared dead, IPOA Vice Chairperson Ann Wanjiku told a Senate hearing, adding that the IPOA attended Ojwang's post mortem examination.

"We are committed to ensuring that everyone who was involved in the crime is brought to justice expeditiously and that no interference from any quarter is brought to bear on the investigation," Interior Minister Kipchumba Murkomen told the Senate.

--Reuters--